Black Wraith King

Bound to Dark Duty. The wraith king is neither living nor dead, but is of both worlds. It can simultaneously perceive and effect the material plane and the ethereal plane.

If the wraith king is reduced to 0 hit points, it isn't killed but is banished without form to the ethereal plane instead. It reforms without weapons or armour in the nearest place of evil after 1d10 days.

Aura of Dread. Any creature hostile to the wraith king that starts its turn within 60 feet of the wraith must make a DC 18 Wisdom saving throw, unless the wraith is incapacitated. On a failed save, the creature is frightened until the start of its next turn. If a creature's saving throw is successful, the creature is immune to the wraith king's Fear Aura for the next 24 hours.

Magic Resistance. The wraith king has advantage on saving throws against spells and other magical effects, and is immune to any spell or effect that would alter its form.

Poisoned Touch. A creature that hits the wraith king with a non-magical melee weapon attack, or an attack that does not deal fire, lightning, or radiant damage, must succeed on a DC 18 Constitution saving throw or be poisoned and instantly suffer three levels of exhaustion.

While poisoned in this way, a creature cannot recover levels exhaustion without being subject to a DC 18 Medicine check. A successful Medicine check and a long rest recovers one level of exhaustion. The poisoned condition ends after three successful Medicine checks. These checks must be at least 24 hours apart and do not need to be consecutive.

On a success save, the creature is not poisoned and suffers only one level of exhaustion.

Multiattack. The wraith king makes two attacks with its longsword.

Longsword. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) slashing damage, or 8 (1d10 + 3) slashing damage if used with two hands.

Dread Mace. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage and the target must succeed on a DC 16 Strength saving throw or be knocked prone.

Witch Blade. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 5 (1d4 + 3) piercing damage and the target is poisoned. While poisoned in this way, the target suffers 1 level of exhaustion at the end of every hour. If is reaches 6 levels of exhaustion, it becomes a wraith under the wraith king's control. This poison can be slowed by a successful 18 Medicine check, so that the target suffers a level of exhaustion once every 3 hours instead, but can only be removed by a greater restoration spell.

Piercing Screech (recharge 5-6). The wraith king emits a soul-piercing screech that saps the resolve of creatures who hear it. Each creature of the wraith's choice that is able to hear the wraith must succeed on a DC 19 Wisdom saving throw or become incapacitated until the end of their next turn, and are 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 has advantage on subsequent saving throws against the wraith's Piercing Screech for the next 24 hours.

Your Power is Broken (recharge 6). The wraith gestures towards a target object it can see within 120 feet and attempts to destroy it. If the object is being held by a creature, the creature makes a DC 19 Charisma saving throw, negating the effect of this ability on a success. A non-magical object that is large or smaller that is afflicted by this ability is automatically destroyed. If the object is larger than this, or if it is magical, it instead loses any magical resistance it has before suffering 17 (2d10 + 6) force damage, and becomes vulnerable to all subsequent forms of damage until the end of the wraith's next turn.

An object destroyed while this ability is active shatters into 1-inch pieces in a flash of light, and cannot be mended by any means short of a wish spell.

Sorcerous Fire. The wraith king uses a bonus action to brandish his sword and wreathe the blade in hellish fire which lasts for 1 minute or until the wraith king loses concentration on the effect. While active, the flames shed dim light in a 20 foot radius, and attacks made with the longsword deal an extra 5 (1d10) fire damage.

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

Retaliation. The wraith king makes one melee weapon attack.

Crushing Blow (2 actions). The wraith king makes one melee weapon attack with either its Mace or its longsword. The attack has a -5 penalty to its attack roll and a +10 bonus to its weapon damage. If the attack hits or fails by 1, any non-magical armour or shield worn by the target suffers a permanent -1 penalty to its AC bonus. If the bonus is reduced sufficiently to render the armour or shield useless, it is destroyed.

Arcing Swing (2 actions). The wraith king swings its mace in a sweeping attack. It makes a single weapon attack against two targets within reach that are within 10 feet of each other.

Assault Resolve (3 actions). The wraith king's Piercing Screech instantly recharges and the he uses it.