Nihilethic Dominator

Ghostly Body (Void Ghost Form Only). The nihilethic dominator has resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks. In addition, the dominator can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.

Undead Fortitude. If damage reduces the nihilethic dominator to 0 hp, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the dominator drops to 1 hp instead.

Undead Nature. The nihilethic dominator doesn't require air, food, drink, or sleep.

Multiattack. The nihilethic dominator makes three Claw attacks, or it makes two Tendril of the Void attacks.

Claw (Undead Form Only). Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 12 (2d8 + 3) slashing damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be knocked prone.

Tendril of the Void (Void Ghost Form Only). Melee Weapon Attack: +6 to hit, reach 10 ft., one creature. Hit: 7 (1d8 + 3) cold damage plus 7 (2d6) necrotic damage.

Void Shape. The nihilethic dominator magically transforms into a dark purple, Void ghost form or back into its Undead form. Its statistics, other than its speed and resistances, are the same in each form. Any equipment it is wearing or carrying changes with it. It reverts to its Undead form of it dies.

Void Body. When the nihilethic dominator takes damage that isn't radiant, it can reduce the damage by 1d12.