Kael’nar the Betrayer

Medium undead, chaotic evil

Traits

Undead Fortitude. If damage reduces Kael’nar to 0 hit points, he can make a Constitution saving throw (DC 5 + damage taken) to drop to 1 hit point instead.

Unstable Necromantic Core. At the end of each of Kael’nar’s turns, roll a d6. On a 1, his core surges uncontrollably. Each creature within 20 feet of him must make a DC 18 Constitution saving throw, taking 14 (4d6) necrotic damage on a failed save, or half as much on a success. This includes his allies and summoned undead.

Legendary Resistance (3/Day). If Kael’nar fails a saving throw, he can choose to succeed instead.

Spellcasting. Kael’nar is a 17th-level spellcaster. His spellcasting ability is Charisma (spell save DC 21, +13 to hit with spell attacks). He requires no material components. He has the following spells prepared:

• Cantrips (at will): chill touch, mage hand, prestidigitation, minor illusion
• 1st level (4 slots): shield, mage armor, detect magic, hex
• 2nd level (3 slots): mirror image, hold person, misty step
• 3rd level (3 slots): counterspell, vampiric touch, fear
• 4th level (3 slots): blight, greater invisibility
• 5th level (2 slots): cloudkill, wall of force
• 6th level (1 slot): circle of death
• 7th level (1 slot): finger of death
• 8th level (1 slot): power word stun

Actions

Necrotic Pulse (Recharge 5–6). Kael’nar unleashes a wave of unstable necrotic energy. Each creature of his choice in a 60-foot radius must make a DC 21 Constitution saving throw. On a failure, a creature takes 45 (10d8) necrotic damage and is stunned until the end of its next turn. On a success, a creature takes half damage and is not stunned.

Rotting Touch. Melee Spell Attack: +13 to hit, reach 5 ft., one target. Hit: 28 (6d8) necrotic damage. The target’s hit point maximum is reduced by the damage taken. This reduction lasts until the target finishes a long rest.

Summon the Dead (1/Day). Kael’nar summons undead allies. Choose one option:

• 4 Wights
• 2 Death Knights
• 8 Wraiths
  The undead appear in unoccupied spaces within 60 feet and obey Kael’nar's verbal commands. They remain for 10 minutes or until destroyed.

Legendary Actions

Kael’nar 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. Kael’nar regains spent legendary actions at the start of his turn.

• Ghost Step. Kael’nar teleports up to 30 feet to an unoccupied space he can see.
• Cantrip. Kael’nar casts a cantrip.
• Unstable Flare (Costs 2 Actions). One creature within 30 feet must make a DC 21 Constitution saving throw or take 22 (5d8) necrotic damage and be blinded until the end of its next turn.
• Cast a Spell (Costs 3 Actions). Kael’nar casts a spell from his list, using a spell slot as normal.

Lair Actions

When in his lair, Kael’nar can invoke the power of his corrupted sanctum. On initiative count 20 (losing initiative ties), he uses one of the following magical effects:

• Twisting Shadows. Shadowy tendrils lash out at creatures of Kael’nar’s choice within 60 feet. Each must succeed on a DC 18 Dexterity saving throw or be restrained until the end of their next turn.
• Necrotic Feedback. Until the next initiative count 20, whenever a creature casts a spell (not an undead), they take 2d10 necrotic damage per level of the spell.
• Grave Uprising. 1d4 Specters or 1 Wight claw their way out of the ground in unoccupied spaces in the lair.

Description

Kael’nar was once a brilliant mage who sought lichdom. His ritual failed, leaving him a being of fractured soul and unstable necrotic power. Violet-black veins pulse across his body, and a broken phylactery shard beats like a twisted heart in his chest. He is tragic, unstable, and utterly lethal.