Guide to the Gargantuan:
Ancient Red Dragon
This is a quick sample overview on how I attempt to make D&D combat more engaging when running Gargantuan creatures. I don’t pay much attention to CR when designing encounters as I find that it can be quite misleading and it’s easier for me to build monsters by assessing my group, so be sure to gauge whether these creatures would be a fair challenge for your players and tune up or down accordingly.
Note: I generally add about 50% health to all gargantuan creatures in order to account for area of effect abilities and to increase the challenge.
Body Parts
The total hit points of body parts are tied to the creature’s overall health; however, the creature doesn’t take any damage dealt to a body part to it’s full form until the body part in question is reduced to 0 health. Often the body parts separately have more health than the creature does overall, this reflects how some damage to extremities and non-critical regions don’t effect the creature until they are completely destroyed.
Example: One of the Ancient Red Dragon’s wing joints has 82 health; the dragon will lose 82 health from it’s total 819 once the wing itself is reduced to 0 hit points. In addition to that, the dragon will be reduced to half flying speed.
Area of Effect Damage
If an area of effect spell would strike more than one body part the creature rolls one saving throw (apply saves and resistances) and then increase the total damage by 25% per body part hit and split the damage among them.
Example: The Ancient Red Dragon is struck by a Meteor Swarm that hits its left side (body, wing, front, and hind leg). The Dragon succeeds its saving throw. The player rolls 140 damage, which is quartered due to the save and resistance to 35, and is then increased by 100% to 70. Each of the four affected body parts take 18 points of damage.
Climbing
A player may attempt to climb a Gargantuan creature by making an Athletics check against a DC based on the type of skin a creature has.
- Feathers, Hairs, or Wood: DC 15
- Scales: DC 17
- Rough Hide: DC 19
- Slimy, Slippery, or Smooth: DC 21
Multiattack
When a creature loses body parts (when they are reduced to 0 health), those body parts are removed from their multiattack.
Example: An Ancient Red Dragon can make a Terrifying Roar, a Bite attack, and two Claw attacks. If it’s mouth and front left leg are reduced to 0 health its multiattack becomes Terrifying Roar and one Claw attack.
Legendary Actions
If the creature loses all its offensive legendary actions due to damage it can spend 3 of its legendary actions to perform one of its normal actions.
Example: The players have destroyed the dragon's wings and tail, leaving it few other actions to take. It uses it can now use its legendary action to make claw, bite, or Fire Breath attacks.
Variable Armor Class
Many creatures are more or less armored in different areas, many of the body parts listed have differing AC scores due to this and some even have two AC scores to give direction for players attack a larger body part in different ways.
Example: Our red dragon's tail has an AC of 24 (scales) and 20 (hide). AC 24 is meant to represent the top of the tail, which is covered in strong, hardened, scale; whereas, AC 20 is meant to represent the comparatively softer and less armored underside of the dragon.
Deadly Synergy
Be aware of how skills work together. These changes can create an incredibly difficult encounter for unprepared adventurers. For instance, once the Ancient Red Dragon’s wings, tail, and maw are destroyed it can use its Fire Breath twice each round. This will allow it to ramp up its Burning Aura rapidly. These types of bosses work well with parties that spend time investigating the threats that lay before them or parties that want to experience highly difficult challenges.
Ancient Red Dragon
Gargantuan dragon, chaotic evil
- Armor Class 24 (scales, natural armor)
- Armor Class 20 (hide, natural armor)
- Hit Points 819 (54d20 + 252)
- Speed 10 ft.
STR DEX CON INT WIS CHA 30 (+10) 10 (+0) 29 (+9) 18 (+4) 15 (+2) 23 (+6)
- Saving Throws Dex +7, Con +16, Wis +9, Cha +13
- Skills Perception +6, Stealth +7
- Damage Immunities fire
- Senses blindsight 60 ft., passive Perception 16
- Languages Common, Draconic
- Challenge so much
Gargantuan. The dragon is comprised of various parts that grant it actions and abilities.
Actions
Multiattack. The dragon can use its Terrifying Roar, it then makes three attacks: one with its bite and two with its claws.
Legendary Actions
The dragon can take 3 legendary actions, choosing from the options presented in the body parts section below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The dragon regains spent legendary actions at the start of its turn.
Body Part Listing:
Ancient Red Dragon
The following is a list of the body parts belonging to the Ancient Red Dragon as well as the statistics of each part and the ability provided to the dragon. If the body part is destroyed the dragon loses said ability unless otherwise stated. The dragon may have more than one of the same body part, for example eyes, it gains the benefit of these parts multiple times.
Snout
- Armor Class 24 (scales, natural armor)
- Hit Points 41
Legendary Action
Detect. The dragon makes a Wisdom (Perception) check.
Eyes (2)
- Armor Class 30 (ranged) 20 (melee)
- Hit Points 41
- Skills Perception +5
- Senses Darkvision 60 ft., passive Perception +5
Crown Scales (1d4)
- Armor Class 30 (ranged) 20 (melee)
- Hit Points 20
Legendary Resistance (Recharge 5-6). If the dragon fails a saving throw, it can choose to succeed instead. The dragon must roll 5 or higher on a 1d6 + Crown Scale Total to recharge this ability. Once all the Crown Scales are destroyed the dragon loses this ability.
Maw
- Armor Class 30 (ranged) 20 (melee)
Actions
Bite. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing plus 14 (4d6) fire damage.
Special Rule. Every physical attack (slashing, piercing, or bludgeoning) that deals 30 or more damage in a single hit breaks one tooth, reducing the damage done by the dragon’s bite attack by 1. If this damage is reduced by 10, the dragon no longer uses its bite attack and becomes enraged. While enraged, the dragon no longer needs to recharge its Fire Breath.
Throat Vent
- Armor Class 24 (scales, natural armor)
- Hit Points 82
Burning Aura. Each creature that ends its turn within 10 feet of the dragon takes 10 fire damage. Each time the dragon uses Fire Breath, increase this damage by 5. If the throat vent is reduced to 0 hit points, increase the damage of Burning Aura by an additional 10 fire damage.
Actions
Terrifying Roar. Each creature of the dragon's choice that is within 120 feet of the dragon and can hear it must succeed on a DC 21 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 of itself on a success. If a creatures saving throw is successful or the effect ends for it, the creature is immune to the dragon's Terrifying Roar for the next 24 hours.
Fire Breath (Recharge 5-6). The dragon exhales fire in a 90-foot cone. Each creature in that area must make a DC 24 Dexterity saving throw, taking 91 (26d6) fire damage on a failed save, or half as much damage on a successful one. If the throat vent is reduced to 0 hit points, Fire Breath does half damage.
Front Legs (2)
- Armor Class 24 (scales, natural armor)
- Hit Points 123
- Speed climb 20 ft.
Actions
Claw. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 17 (2d6 + 10) slashing damage.
Hind Legs (2)
- Armor Class 24 (scales, natural armor)
- Hit Points 123
- Speed 15 ft.
Tail
- Armor Class 24 (scales, natural armor)
- Armor Class 20 (hide, natural armor)
- Hit Points 123
Actions
Tail. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage.
Legendary Actions
Tail Attack. The dragon makes a tail attack.
Wings (2)
- Armor Class 24 (scales, natural armor)
- Hit Points 82
- Speed fly 40 ft.
Legendary Actions
Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 25 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.