Chamiabac, Lord of Bones

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

Special Equipment. Chamiabac carries a Staff named Boneshaft. In the hands of anyone other than Chamiabac , Boneshaft is a +2 Club.

Multiattack. Chamiabac uses Bone Spray (if available), Bone Prison, or Spellcasting. He then makes two attacks with Boneshaft.

Boneshaft. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 7 (1d4 + 5) bludgeoning damage plus 9 (2d8) necrotic damage. If the target is a creature, it is afflicted by entropic magic, taking 9 (2d8) necrotic damage at the start of each of its turns. Immediately after taking this damage on its turn, the target must make a DC 20 Constitution saving throw, ending the effect on itself on a success. Until it succeeds on this save, the afflicted target can’t regain hit points.

Bone Spray(Recharge 5–6). Chamiabac conjures a torrent of piercing bone spears that fill a 120-foot cone and pass through all creatures in that area before dissipating. Each creature in that area must make a DC 22 Constitution saving throw. On a failed save, the creature takes 36 (8d8) necrotic damage and cannot regain hit points until Chamiabac's next turn. On a successful save, the creature takes half as much damage only.

Bone Prison. Chamiabac causes giant bone claws to rise out of the earth and engulf one creature he can see within 120 feet of himself. The target must make a DC 22 Dexterity saving throw, taking 24 (3d8 + 10) necrotic damage and having the restrained condition on a failed save, or half as much damage on a successful one. A Humanoid killed while in this prison rises as a wight at the start of Chamiabac's next turn and acts immediately after Chamiabac in the initiative order. The wightis under Chamiabac's control.

Spellcasting. Vecna casts one of the following spells, requiring no material components and using Intelligence as the spellcasting ability (spell save DC 22):

At will: Animate Dead, Cause Fear, Dispel Magic, Spirit Shroud, Lightning Bolt, Mage Hand, Prestidigitation

2/day each: Blindness/Deafness, Blight, Negative Energy Flood

1/day each: Finger of Death, Globe of Invulnerability, Circle of Death, Abi-Dalzim's Horrid Wilting 

Vile Teleport. Chamiabac teleports, along with any equipment he is wearing or carrying, up to 30 feet to an unoccupied space he can see. He can cause each creature of his choice within 15 feet of his destination space to take 10 (3d6) psychic damage. If at least one creature takes this damage, Chamiabac regains 80 hit points.

Boneshaft. Chamiabac makes a melee attack with Boneshaft

Spellcasting (3 Legendary Actions). Chamiabac casts one spell without expending a use

Dread Counterspell. Chamiabac utters a dread word to interrupt a creature he can see that is casting a spell. If the spell is 4th level or lower, it fails and has no effect. If the spell is 5th level or higher, Chamiabac makes an Intelligence check (DC 10 plus the spell’s level). On a successful check, the spell fails and has no effect. Whatever the spell’s level, the caster takes 10 (3d6) psychic damage if the spell fails.

Bone Riposte. In response to being hit by an attack, Chamiabac utters a fell word, dealing 10 (3d6) necrotic damage to the attacker, and Chamiabac pushes the attacker up to ten feet away from him

Bone Shift (2  Legendary Actions). Chamiabac teleports, along with any equipment he is wearing or carrying, up to 30 feet to an unoccupied space he can see. He can cause each creature of his choice within 15 feet of his destination space to take 10 (3d6) psychic damage. If at least one creature takes this damage, Chamiabac regains 80 hit points.

Boneshaft. Chamiabac makes a melee attack with Boneshaft

Spellcasting (2 Legendary Actions). Chamiabac casts one spell without expending a use