Better Greatwyrms

White Greatwyrm

Gargantuan dragon (chromatic), chaotic evil

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• Armor Class 22 (natural armor)
• Hit Points 487 (25d20 + 225)
• Speed 60 ft., burrow 60 ft., fly 120 ft., swim 60 ft.

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STR	DEX	CON	INT	WIS	CHA
30 (+10)	12 (+1)	28 (+9)	18 (+4)	22 (+6)	17 (+3)

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• Saving Throws Dex +9, Con +17, Wis +14, Cha +11
• Skills Intimidation +19, Perception +22, Stealth +9
• Damage Immunities cold
• Condition Immunities charmed, exhaustion, frightened
• Senses truesight 120 ft., passive Perception 32
• Languages Common, Draconic
• Challenge 25 (75,000 XP, or 150,000 XP as a mythic encounter)
• Proficiency Bonus +8

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Absolute Zero (Mythic Trait; Once Per Rest). If the greatwyrm would be reduced to 0 hit points, it instead resets to maximum hit points, and it can end any spells of its choice on itself. It then unleashes a blast of elemental cold in a 120 foot radius. Each creature in the area must succeed on a DC 25 Constitution saving throw or be restrained until the end of the dragon's next turn.

Brutish Durability. Whenever the greatwyrm makes a saving throw, it can roll a d10 and add the result to the total.

Draconic Might. The greatwyrm's weapon attacks are magical and deal quadruple damage to objects and structures. When it hits a target with a melee attack, if the attack roll meets or exceeds the target's passive Strength (Athletics) score, the greatwyrm can push it up to 10 feet away, or 20 feet away if its mythic trait is active.

Ice Walk. The greatwyrm can move across and climb icy surfaces without needing to make an ability check. Additionally, difficult terrain composed of ice or snow doesn't cost it extra moment.

Indomitable (3/Day). The greatwyrm can reroll a saving throw it fails. It must use the new roll.

Actions

Multiattack. The greatwyrm can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 13 (2d12) cold damage, and the target's speed is reduced by 10 feet until the end of its next turn.

Claw. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 19 (2d8 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20) and restrained until this grapple ends. The greatwyrm can have only one creature grappled this way at a time.

Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 26 Strength saving throw or be knocked prone.

Frightful Presence. Each creature of the greatwyrm's choice that is within 1 mile of the dragon and aware of it must succeed on a DC 19 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the greatwyrm's Frightful Presence for the next 24 hours.

Frost Breath (Recharge 5–6). The greatwyrm exhales an icy blast in a 300-foot cone. Each creature and object in that area takes 88 (16d10) cold damage (DC 25 Constitution save for half). Damaged surfaces in this area then become slippery ice (DMG 110) until cleared.

Bonus Actions

Snowstorm (1/Day). The greatwyrm unleashes a magical snowstorm in a 1 mile radius that lasts for 1 hour. Use the blizzard (IDRotF 10) or heavy precipitation (DMG 110) entry to represent its effects. The greatwyrm ignores all effects caused by the snowstorm.

Reactions

Vicious Reprisal. In response to taking damage, the greatwyrm makes a bite attack against a random creature within 5 feet of it. If no creature is within reach, the greatwyrm can attack an object, or it can move up to half its speed toward an enemy it can see, without provoking opportunity attacks.

Legendary Actions

The greatwyrm can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The greatwyrm regains spent legendary actions at the start of its turn.

• Tail Attack. The greatwyrm makes two tail attacks, one of which must be against an object.
• Savage (Costs 2 Actions). The greatwyrm makes a claw attack against each creature and object within 10 feet of it.
• Wing Attack (Costs 2 Actions). The greatwyrm beats its wings. Each creature within 10 feet of the greatwyrm must succeed on a DC 26 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The greatwyrm can then fly up to half its flying speed.

Mythic Actions

If the greatwyrm's mythic trait has activated in the last hour, it can use the options below as legendary actions.

• Fling. One Huge or smaller object held or creature grappled by the greatwyrm is thrown up to 30 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 20 Dexterity saving throw or take the same damage and be knocked prone.
• Icicle Impale. Ranged Spell Attack: +17 to hit, range 60 ft., one target. Hit: 19 (3d6 + 9) piercing damage, and the target's speed is reduced by 10 feet until the end of its next turn.
• Ice Shards (Costs 2 Actions). The greatwyrm causes shards of ice to burst forth from any ice within 120 feet of it. Each creature within 5 feet of that ice takes 9 (2d8) piercing damage plus 9 (2d8) cold damage (DC 25 Dexterity save for half). If the saving throw fails by 5 or more, the target also deals only half damage with weapon attacks that use Strength until the end of its next turn.

Black Greatwyrm

Gargantuan dragon (chromatic), chaotic evil

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• Armor Class 22 (natural armor)
• Hit Points 507 (26d20 + 234)
• Speed 60 ft., burrow 60 ft., fly 120 ft., swim 60 ft.

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STR	DEX	CON	INT	WIS	CHA
30 (+10)	14 (+2)	28 (+9)	22 (+6)	21 (+5)	24 (+7)

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• Saving Throws Dex +10, Con +17, Wis +13, Cha +15
• Skills Intimidation +23, Perception +21, Stealth +10
• Damage Immunities acid
• Condition Immunities charmed, exhaustion, frightened
• Senses truesight 120 ft., passive Perception 31
• Languages Common, Draconic
• Challenge 26 (90,000 XP, or 180,000 XP as a mythic encounter)
• Proficiency Bonus +8

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Draconic Might. The greatwyrm's weapon attacks are magical and deal quadruple damage to objects and structures. When it hits a target with a melee attack, if the attack roll meets or exceeds the target's passive Strength (Athletics) score, the greatwyrm can push it up to 10 feet away, or 20 feet away if its mythic trait is active.

Feign Weakness (Mythic Trait; Once Per Rest). If the greatwyrm dies, it shrieks in pain as its body melts into a puddle of acid and filth. Its body then reforms from this puddle at the start of its next turn, resetting to maximum hit points, ending any spells of its choice on itself, and becoming active again. The greatwyrm then moves up to its speed (without provoking opportunity attacks) towards the creature that killed it, and makes one claw attack against it if possible.

Stench. At the start of each of the greatwyrm's turns, each creature within 30 feet of it must succeed on a DC 25 Constitution saving throw or be poisoned until the start of its next turn. On a successful saving throw, the creature is immune to the greatwyrm's stench for 24 hours.

Unbreakable. If the greatwyrm is incapacitated, poisoned, or restrained at the start of its turn, any effects causing these conditions immediately end on the greatwyrm.

Actions

Multiattack. The greatwyrm can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 13 (2d12) acid damage.

Claw. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 19 (2d8 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20) and restrained until this grapple ends. The greatwyrm can have only one creature grappled this way at a time.

Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 26 Strength saving throw or be knocked prone.

Frightful Presence. Each creature of the greatwyrm's choice that is within 1 mile of the dragon and aware of it must succeed on a DC 23 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the greatwyrm's Frightful Presence for the next 24 hours.

Corrosive Breath (Recharge 5–6). The greatwyrm exhales acid in a 300-foot line that is 20 feet wide. Each creature and object in that area takes 88 (16d10) acid damage (DC 25 Dexterity save for half). Damaged surfaces in this area then become corrosive acid pools until cleared. Any creature or object that touches one of these surfaces takes 11 (2d10) acid damage; a target can't take this damage more than once per round.

Bonus Actions

Rampage. When the greatwyrm reduces a creature or a Gargantuan object to 0 hit points with a melee attack on its turn, it can use this bonus action to move up to half its speed and make another attack.

Gas Cloud (1/Day). The greatwyrm unleashes a cloud of toxic gas in a 1 mile radius that lasts for 1 hour. The gas reduces visibility to 120 feet, and everything within that radius is lightly obscured. While in this gas, living creatures are plagued by constant coughing and cannot benefit from resistance to acid or poison. If a living creature dies while in the gas, insects and filth possess its corpse, causing it to rise as a zombie in the same space. The greatwyrm ignores all effects caused by the cloud.

Legendary Actions

The greatwyrm can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The greatwyrm regains spent legendary actions at the start of its turn.

• Tail Attack. The greatwyrm makes two tail attacks, one of which must be against an object.
• Vitriolic Spray. Ranged Spell Attack: +15 to hit, range 90 ft., one target. Hit: 14 (3d4 + 7) acid damage, and the target must succeed on a DC 23 Constitution saving throw or be blinded until the end of its next turn.
• Wing Attack (Costs 2 Actions). The greatwyrm beats its wings. Each creature within 10 feet of the greatwyrm must succeed on a DC 26 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The greatwyrm can then fly up to half its flying speed.

Mythic Actions

If the greatwyrm's mythic trait has activated in the last hour, it can use the options below as legendary actions.

• Fling. One Huge or smaller object held or creature grappled by the greatwyrm is thrown up to 30 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 20 Dexterity saving throw or take the same damage and be knocked prone.
• Corrosive Decay (Costs 2 Actions). The greatwyrm unleashes a burst of rot and acid in a 20-foot-radius, 40-foot-high cylinder centered on a point within 90 feet of it. Each creature and object in the area takes 22 (4d10) acid damage (DC 25 Dexterity save for half). Objects in the area become permanently vulnerable to all damage, and each creature that takes this damage suffers disadvantage on Strength and Constitution saving throws until the end of the greatwyrm's next turn.
• Summon Shambling Mound (Costs 2 Actions). The greatwyrm magically creates a shambling mound in an unoccupied space within 30 feet of it. The shambling mound takes its turn on initiative count 20 (losing initiative ties) each round and carries out the greatwyrm's malefic will to the best of its ability.

Green Greatwyrm

Gargantuan dragon (chromatic), lawful evil

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• Armor Class 22 (natural armor)
• Hit Points 526 (27d20 + 243)
• Speed 60 ft., burrow 60 ft., fly 120 ft., swim 60 ft.

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STR	DEX	CON	INT	WIS	CHA
30 (+10)	15 (+2)	28 (+9)	26 (+8)	21 (+5)	24 (+7)

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• Saving Throws Dex +10, Con +17, Int +16, Wis +13, Cha +15
• Skills Deception +15, Insight +13, Intimidation +23, Perception +21, Persuasion +15, Stealth +18
• Damage Immunities poison
• Condition Immunities charmed, exhaustion, frightened, poisoned
• Senses truesight 120 ft., passive Perception 31
• Languages Common, Draconic
• Challenge 27 (105,000 XP, or 210,000 XP as a mythic encounter)
• Proficiency Bonus +8

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Deceive the Senses (Mythic Trait; Once Per Rest). If the greatwyrm would be reduced to 0 hit points, it instead resets to maximum hit points, and it can end any spells of its choice on itself. It then becomes invisible until the end of its next turn, and it can immediately move up to its speed and take the Hide action (no reaction required).

Draconic Might. The greatwyrm's weapon attacks are magical and deal quadruple damage to objects and structures. When it hits a target with a melee attack, if the attack roll meets or exceeds the target's passive Strength (Athletics) score, the greatwyrm can push it up to 10 feet away, or 20 feet away if its mythic trait is active.

Guarded Mind. The greatwyrm has advantage on all Intelligence, Wisdom, and Charisma saving throws.

Plant Stride. The greatwyrm ignores difficult terrain caused by plants and can't take damage from them if they are nonmagical.

Actions

Multiattack. The greatwyrm can use its Corrupting Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 13 (2d12) poison damage.

Claw. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 19 (2d8 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20), restrained, and has disadvantage on Intelligence, Wisdom, and Charisma saving throws until this grapple ends. The greatwyrm can have only one creature grappled this way at a time.

Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 27 Strength saving throw or be knocked prone.

Corrupting Presence. Each creature of the greatwyrm's choice that is within 1 mile of the dragon and aware of it must succeed on a DC 23 Wisdom saving throw or become charmed or frightened (greatwyrm's choice) for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the greatwyrm's Corrupting Presence for the next 24 hours.

Noxious Breath (Recharge 5–6). The greatwyrm exhales poison in a 300-foot cone. Each creature and object in that area takes 91 (26d6) poison damage (DC 25 Constitution save for half). Damaged surfaces in this area then grow thick vines that grasp at nearby creatures until cleared. Any Large or smaller creature that ends its turn within 5 feet of these vines is grappled by them (escape DC 15).

Bonus Actions

Brain Fog (1/Day). The greatwyrm unleashes a cloud of poisonous fog in a 1 mile radius that lasts for 1 hour. The gas lightly obscures the area, and living creatures in the area cannot benefit from resistance to poison or psychic damage and have disadvantage on all Intelligence, Wisdom, and Charisma checks. The greatwyrm ignores all effects caused by the fog.

Reactions

Feed on Weakness. When a creature within 20 feet of the greatwyrm fails an Intelligence, Wisdom, or Charisma saving throw, the greatwyrm gains 15 temporary hit points.

Legendary Actions

The greatwyrm can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The greatwyrm regains spent legendary actions at the start of its turn.

• Tail Attack. The greatwyrm makes two tail attacks, one of which must be against an object.
• Luring Glare. The dragon targets one creature it can see within 90 feet of it. The target must make a DC 24 Wisdom saving throw. The target has disadvantage on the save if it is poisoned. On a failed save, the target must use its reaction to move up to half its speed along a path of the dragon's choice.
• Wing Attack (Costs 2 Actions). The greatwyrm beats its wings. Each creature within 10 feet of the greatwyrm must succeed on a DC 26 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The greatwyrm can then fly up to half its flying speed.

Mythic Actions

If the greatwyrm's mythic trait has activated in the last hour, it can use the options below as legendary actions.

• Nimble Predator. The greatwyrm moves up to 30 feet without provoking opportunity attacks.
• Fling. One Huge or smaller object held or creature grappled by the greatwyrm is thrown up to 30 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 20 Dexterity saving throw or take the same damage and be knocked prone.
• Mind Poison (Costs 2 Actions). The greatwyrm unleashes a mental assault against all creatures within a 20-foot-radius sphere centered on a point within 90 feet of it. Each target takes 22 (4d10) psychic damage (DC 24 Intelligence save for half). On a failed save, a target is also poisoned until the end of the greatwyrm's next turn.

Blue Greatwyrm

Gargantuan dragon (chromatic), lawful evil

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• Armor Class 22 (natural armor)
• Hit Points 546 (28d20 + 252)
• Speed 75 ft., burrow 75 ft., fly 150 ft., swim 75 ft.

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STR	DEX	CON	INT	WIS	CHA
30 (+10)	14 (+2)	28 (+9)	24 (+7)	21 (+5)	26 (+8)

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• Saving Throws Dex +10, Con +17, Int +15, Wis +13, Cha +16
• Skills Arcana +15, Intimidation +24, Perception +21, Stealth +10
• Damage Immunities lightning
• Condition Immunities charmed, exhaustion, frightened, poisoned
• Senses tremorsense 30 ft., truesight 120 ft., passive Perception 31
• Languages Common, Draconic
• Challenge 28 (120,000 XP, or 240,000 XP as a mythic encounter)
• Proficiency Bonus +8

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Destructive Wrath (Mythic Trait; Once Per Rest). If the greatwyrm would be reduced to 0 hit points, it instead resets to maximum hit points, and it can end any spells of its choice on itself. It then unleashes a huge burst of thunder that concusses each creature and object within 120 feet of it. Each target takes 14 (4d6) thunder damage (DC 25 Constitution saving throw for half) and is pushed up to 20 feet away from the greatwyrm. On a failed save, a target is also knocked prone.

Draconic Might. The greatwyrm's weapon attacks are magical and deal quadruple damage to objects and structures. When it hits a target with a melee attack, if the attack roll meets or exceeds the target's passive Strength (Athletics) score, the greatwyrm can push it up to 10 feet away, or 20 feet away if its mythic trait is active.

Magic Resistance. The greatwyrm has advantage on saving throws against spells and other magical effects.

Supercharged. If a creature touches the greatwyrm or hits it with a melee attack while within 15 feet of it, or if it targets the dragon with a spell that it isn't a willing target of, the creature takes 7 (2d6) lightning damage.

Thunderous Charge (1/Turn). If the greatwyrm moves at least 15 feet straight toward a target and then hits it with a gore attack on the same turn, the target also takes 26 (4d12) thunder damage.

Actions

Multiattack. The greatwyrm can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 13 (2d12) lightning damage.

Claw. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 19 (2d8 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20) and restrained until this grapple ends. The greatwyrm can have only one creature grappled this way at a time.

Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 27 Strength saving throw or be knocked prone.

Gore. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 36 (4d12 + 10) piercing damage.

Frightful Presence. Each creature of the greatwyrm's choice that is within 1 mile of the dragon and aware of it must succeed on a DC 24 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the greatwyrm's Frightful Presence for the next 24 hours.

Storm Breath (Recharge 5–6). The greatwyrm exhales concentrated storm energy in a 300-foot line that is 20 feet wide. Each creature and object in that area takes 88 (16d10) lightning damage (DC 25 Dexterity save for half). If a Huge or smaller target fails this save by 5 or more, it is also pushed up to 30 feet away from the greatwyrm.

Bonus Actions

Superstorm (1/Day). The greatwyrm unleashes a violent storm in a 1 mile radius that lasts for 1 hour. The storm is either a rainstorm or a sandstorm, depending on the features of the surrounding environment. Strong wind (DMG 110) batters the area and causes any creature in it that is knocked prone to also be flung up to 30 feet in a random direction. The greatwyrm ignores all effects caused by the storm.

Legendary Actions

The greatwyrm can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The greatwyrm regains spent legendary actions at the start of its turn.

• Tail Attack. The greatwyrm makes two tail attacks, one of which must be against an object.
• Thunder Bolt. Ranged Spell Attack: +16 to hit, range 90 ft., one target. Hit: 15 (2d6 + 8) lightning damage plus 3 (1d6) thunder damage. On a critical hit, the target must also succeed on a DC 24 Constitution saving throw or become stunned until the end of the dragon's next turn.
• Wing Attack (Costs 2 Actions). The greatwyrm beats its wings. Each creature within 10 feet of the greatwyrm must succeed on a DC 26 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The greatwyrm can then fly up to half its flying speed.

Mythic Actions

If the greatwyrm's mythic trait has activated in the last hour, it can use the options below as legendary actions.

• Fling. One Huge or smaller object held or creature grappled by the greatwyrm is thrown up to 30 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 20 Dexterity saving throw or take the same damage and be knocked prone.
• Lightning Strike (Costs 2 Actions). The greatwyrm causes a bolt of lightning to strike a point on the ground within 120 feet of it. Each creature and object within 5 feet of that point takes 26 (4d12) lightning damage (DC 24 Dexterity save for half). If the save fails by 5 or more, a creature is also deafened until the end of the greatwyrm's next turn.
• Summon Air Elemental (Costs 2 Actions). The greatwyrm magically creates an air elemental in an unoccupied space within 30 feet of it. The air elemental takes its turn on initiative count 20 (losing initiative ties) each round and carries out the greatwyrm's malefic will to the best of its ability.

Red Greatwyrm

Gargantuan dragon (chromatic), chaotic evil

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• Armor Class 22 (natural armor)
• Hit Points 565 (29d20 + 261)
• Speed 60 ft., burrow 60 ft., fly 120 ft., swim 60 ft.

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STR	DEX	CON	INT	WIS	CHA
30 (+10)	14 (+2)	29 (+9)	24 (+7)	20 (+5)	28 (+9)

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• Saving Throws Dex +11, Con +18, Int +16, Wis +14, Cha +18
• Skills Intimidation +27, Perception +23, Stealth +11
• Damage Immunities fire
• Condition Immunities charmed, exhaustion, frightened, poisoned
• Senses truesight 120 ft., passive Perception 33
• Languages Common, Draconic
• Challenge 29 (135,000 XP, or 270,000 XP as a mythic encounter)
• Proficiency Bonus +9

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Draconic Might. The greatwyrm's weapon attacks are magical and deal quadruple damage to objects and structures. When it hits a target with a melee attack, if the attack roll meets or exceeds the target's passive Strength (Athletics) score, the greatwyrm can push it up to 10 feet away, or 20 feet away if its mythic trait is active.

Fiery Rebirth (Mythic Trait; Once Per Rest). If the greatwyrm dies, its body burns away into a pile of ashes. Its body then reforms from these ashes at the start of its next turn, resetting to maximum hit points, ending any spells of its choice on itself, and becoming active again. When this happens, each creature that can see the greatwyrm must succeed on a DC 27 Constitution saving throw or take 14 (4d6) fire damage and be blinded until the end of the greatwyrm's next turn.

Shrug it Off. At the start of each of its turns, the greatwyrm can end one condition on itself, provided it has at least 1 hit point.

Spreading Magma. Some of the greatwyrm's features might cause magma to burst forth from a surface, making it molten for a time. While molten, the surface is difficult terrain, and any creature that ends its turn while touching it takes 14 (4d6) fire damage.

Actions

Multiattack. The greatwyrm can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 13 (2d12) fire damage.

Claw. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 19 (2d8 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20) and restrained until this grapple ends. The greatwyrm can have only one creature grappled this way at a time.

Tail. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 27 Strength saving throw or be knocked prone.

Frightful Presence. Each creature of the greatwyrm's choice that is within 1 mile of the dragon and aware of it must succeed on a DC 26 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the greatwyrm's Frightful Presence for the next 24 hours.

Inferno Breath (Recharge 5–6). The greatwyrm exhales fire in a 300-foot cone. Each creature and object in that area takes 91 (26d6) fire damage (DC 26 Dexterity save for half). Damaged surfaces in the area become molten until the end of the greatwyrm's next turn.

Bonus Actions

Rain of Fire (1/Day). The greatwyrm causes fiery meteors to rain down on an area in a 1 mile radius that lasts for 1 hour. Small meteor impacts cause every creature and object exposed to the sky to take 2 (1d4) fire damage at the start of each of the greatwyrm's turns.
 Additionally, when a creature or object drops to 0 hit points while in the storm, magma explodes out from it, causing the area within 10 feet of it to become molten until cleared.

Legendary Actions

The greatwyrm can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The greatwyrm regains spent legendary actions at the start of its turn.

• Tail Attack. The greatwyrm makes two tail attacks, one of which must be against an object.
• Flame Blast. Ranged Spell Attack: +18 to hit, range 90 ft., one target. Hit: 17 (2d8 + 8) fire damage. On a critical hit, the target has disadvantage on saving throws against fire damage until the end of the dragon's next turn. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.
• Wing Attack (Costs 2 Actions). The greatwyrm beats its wings. Each creature within 10 feet of the greatwyrm must succeed on a DC 26 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The greatwyrm can then fly up to half its flying speed.

Mythic Actions

If the greatwyrm's mythic trait has activated in the last hour, it can use the options below as legendary actions.

• Chosen of Tiamat. Channeling the power of the mother of dragons herself, the greatwyrm grants itself advantage on the next saving throw it makes before the end of its next turn.
• Fling. One Huge or smaller object held or creature grappled by the greatwyrm is thrown up to 30 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 20 Dexterity saving throw or take the same damage and be knocked prone.
• Volcanic Eruption (Costs 2 Actions). The greatwyrm causes lava to erupt from every molten surface within 120 feet of it. Each creature and object within 10 feet of a molten surface when this happens takes 14 (4d6) bludgeoning damage plus 14 (4d6) fire damage (DC 26 Dexterity save for half). If the save fails by 5 or more, a creature is also knocked prone.

Tiamat

Gargantuan dragon (chromatic, deity), chaotic evil

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• Armor Class 23 (natural armor)
• Hit Points 574 (28d20 + 280)
• Speed 60 ft., burrow 60 ft., fly 120 ft., swim 60 ft.

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STR	DEX	CON	INT	WIS	CHA
30 (+10)	14 (+2)	30 (+10)	21 (+5)	20 (+5)	26 (+8)

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• Saving Throws Dex +11, Con +19, Wis +14, Cha +17
• Skills Intimidation +26, Perception +23
• Damage Immunities acid, cold, fire, lightning, poison; bludgeoning, piercing, and slashing from nonmagical attacks
• Condition Immunities blinded, charmed, deafened, frightened, poisoned, stunned
• Senses truesight 120 ft., blindsight 500 ft., passive Perception 33
• Languages all, telepathy 1,000 ft.
• Challenge 30 (155,000 XP, or 310,000 XP as a mythic encounter)
• Proficiency Bonus +9

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Discorporation. When Tiamat drops to 0 hit points or dies, her body is destroyed but her essence travels back to her domain in the Nine Hells, and she is unable to take physical form for a time.

Divine Will. Tiamat is immune to any spell or effect that would alter her form, as well as those that would read her thoughts, determine if she is lying, or magically influence her thoughts or behavior.

Draconic Might. Tiamat's weapon attacks are magical and deal quadruple damage to objects and structures. When she hits a target with a melee attack, if the attack roll meets or exceeds the target's passive Strength (Athletics) score, Tiamat can push it up to 10 feet away, 20 feet away if one of her mythic traits are active, or 30 feet away if both mythic traits are active.

Dragon Queen's Roar (Mythic Trait; Once Per Rest). If Tiamat would be reduced to 0 hit points, she instead resets to maximum hit points, and she can end any spells of her choice on herself. She then releases a huge roar that decimates the area within 300 feet of her, causing each creature and object of her choice in the area, regardless of size or structural stability, to be pushed up to 60 feet away from Tiamat and knocked prone.

Infernal Dealings (Mythic Trait; Once Per Rest). If Tiamat would be reduced to 0 hit points, she instead resets to maximum hit points, and she can end any spells of her choice on herself. She then regurgitates ten merregons who land in unoccupied spaces within 30 feet of her. The merregons act at the end of the initiative order and defend Tiamat to the best of their ability.

Innate Spellcasting. Tiamat's innate spellcasting ability is Charisma (spell save DC 25). She can innately cast the following spells:

Constant: freedom of movement, nondetection
2/day each: dominate monster, earthquake
1/day each: divine word, wish

Legendary Resistance (5/Day). If Tiamat fails a saving throw, she can choose to succeed instead.

Multiple Heads. Tiamat can take one reaction per turn, rather than only one per round. She also has advantage on saving throws against being knocked unconscious. If she fails a saving throw against an effect that would stun a creature, one of her unspent legendary actions is spent.

Sense Avarice. If a creature Tiamat can see communicates telepathically with her, she learns the creature's greatest desires.

Actions

Catastrophic Breath. Tiamat exhales elemental energy from one of her heads in a 300-foot cone. Each creature and object in that area takes 97 (15d12) damage (DC 27 saving throw for half; see below), with the damage type, save type, and secondary effect determined by which head she used. Once Tiamat chooses a breath weapon for one of her heads, she can't choose another one associated with that head on her next turn.

• White: Frost Breath. The breath does cold damage, and its save type is Constitution. Damaged surfaces in this area then become slippery ice (DMG 110) until cleared.
• Black: Corrosive Breath. The breath does acid damage, and the save type is Dexterity. Damaged surfaces in this area then become corrosive acid pools until cleared. Any creature or object that touches one of these surfaces takes 11 (2d10) acid damage; a target can't take this damage more than once per round.
• Green: Noxious Breath. The breath does poison damage, and the save type is Constitution. Damaged surfaces in this area then grow thick vines that grasp at nearby creatures until cleared. Any Large or smaller creature that ends its turn within 5 feet of these vines is grappled by them (escape DC 15).
• Blue: Storm Breath. The breath does lightning damage, and the save type is Dexterity. If a Huge or smaller target fails this save by 5 or more, it is also pushed up to 30 feet away from the greatwyrm.
• Red: Inferno Breath. The breath does fire damage, and the save type is Dexterity. Damaged surfaces in this area then become molten until the end of the greatwyrm's next turn. While molten, the surface is difficult terrain, and any creature that ends its turn while touching it takes 14 (4d6) fire damage.

Bonus Actions

Apocalypse (1/Day). TIamat unleashes an apocalyptic storm in a 1 mile radius that lasts for 1 hour. The area is battered by heavy precipitation and strong wind, and violent elemental energies cause every creature and object exposed to the storm to take 5 (2d4) acid, cold, fire, lightning, or poison damage (Tiamat's choice) at the start of each of Tiamat's turns. Tiamat, and any elemental effect she creates, is unaffected by the storm.

Corrupting Presence. Each creature of Tiamat's choice that is within 1 mile of the dragon and aware of it must succeed on a DC 25 Wisdom saving throw or become charmed or frightened (Tiamat's choice) for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Tiamat's Corrupting Presence for the next 24 hours.

Tiamat

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Legendary Actions

Tiamat can take 5 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. Tiamat regains spent legendary actions at the start of her turn.

• Nimble Predator. Tiamat moves up to 30 feet without provoking opportunity attacks.
• Bite. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 23 (2d12 + 10) piercing damage plus 19 (3d12) acid, cold, fire, lightning, or poison damage (Tiamat's choice).
• Claw. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20), restrained, and has disadvantage on Intelligence, Wisdom, and Charisma saving throws until this grapple ends. The aspect can have only one creature grappled this way at a time.
• Tail. Melee Weapon Attack: +19 to hit, reach 30 ft., one target. Hit: 23 (2d12 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 27 Strength saving throw or be knocked prone.
• Cast a Spell (Costs 3 Actions). Tiamat casts one of her innate spells.

Mythic Actions

If one of Tiamat's mythic traits were activated in the last hour, she can use the first three options below as legendary actions. If both traits were activated in the last hour, she can instead use any of the options below.

• Divine Greed. Tiamat steals the magic benefiting one creature she can see within 90 feet of her. Any beneficial spell affecting the target of her choice transferred to Tiamat. If a spell she steals requires concentration, Tiamat concentrates on it for the duration instead, but she cannot concentrate on multiple spells simultaneously (as normal).
• Tail Sweep. Tiamat makes a tail attack against each creature and object within 30 feet of her.
• Chilling Gaze (Costs 2 Actions). Tiamat uses her green and white heads to assault each creature of her choice that she can see within a 90-foot cone. Each creature in the area takes 11 (2d10) cold damage plus 11 (2d10) psychic damage (DC 25 Intelligence save for half). On a failed save, a target is also poisoned and has its speed halved until the end of the greatwyrm's next turn.
• Toxic Gas (Costs 2 Actions). Tiamat uses her black and green heads to unleash toxic gas in a 60-foot radius around her. Each creature in that area must succeed on a DC 25 Constitution saving throw or become poisoned until the end of Tiamat's next turn. A creature is blinded and deafened while poisoned in this way.
• Fiery Tornado (Costs 2 Actions). Tiamat uses her blue and red heads to unleash a cyclone in a 30-foot radius centered on a point she can see. Each creature and object in the vortex takes 10 (3d6) fire damage plus 10 (3d6) lightning damage (DC 25 Dexterity save for half). On a failed save, a Huge or smaller creature is also hurled 30 feet in a random direction and knocked prone.
• Hurl Through Hell (Costs 3 Actions). Tiamat targets a creature she is grappling. The creature must succeed on a DC 25 Charisma saving throw or take 44 (8d10) psychic damage and be banished to Avernus (the first layer of the Nine Hells). At the start of Tiamat's next turn, the creature reappears in an unoccupied space within 10 feet of her.