Absalom, High Priest of Dregoth

Change Shape. Absalom can use his action to polymorph into Medium living or undead dragonborn. Other than his speed, Absalon's statistics are the same in each form. Any equipment he is wearing or carrying isn't transformed. Absalom reverts to his true form if he dies.

Eldritch Mind. Absalom has advantage on Constitution saving throws that he makes to maintain concentration on a spell.

Eldritch Sight. Absalom can cast detect magic at will, without expending a spell slot or material components.

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

Magic Resistance. Absalom has advantage on saving throws against spells and other magical effects.

Magic Weapons. Absalom's weapon attacks are magical.

Rejuvenation. Once destroyed, Absalom gains a new body in 24 hours if his heart is intact, regaining all his hit points and becoming active again. The new body appears within 5 feet of Absalom's heart.

Spellcasting. Absalom is a 17th-level spellcaster. His spellcasting ability is Charisma (spell save DC 20, +12 to hit with spell attacks). Absalom has the following Warlock spells prepared:

Cantrips (at will): Eldritch Blast, Green-Flame Blade, Mind Sliver, Toll the Dead

1st-5th level (4 5th-level slots): Cloud of Daggers, Command, Compelled Duel, Compulsion, Crown of Madness, Counterspell, Dimension Door, Dominate Person, Earthbind, Enervation, Fear, Hex, Hold Monster, Mind Spike, Negative Energy Flood, Psychic Lance, Sending, Shadow of Moil, Spirit Shroud, Staggering Smite, Synaptic Static, Tongues, Wrathful Smite

1/Day each: Eyebite, Power Word: Pain, Feeblemind, Power Word: Kill

Undying Servitude. Absalom can cast animate dead without using a spell slot. Once he does so, he can't cast it in this way again until he finishes a long rest.

Multiattack. Absalom makes two attacks with his Sword, and one wither either his Rotting Claws, a spell of 5th level or lower, or his Spirit Siphon if it's available.

Bastard Sword. Melee Weapon Attack: +13, Reach 5 ft., one target. Hit: 12 (1d10 + 7) slashing damage plus 9 (2d8) necrotic damage.

Rotting Claws. Melee Weapon Attack:+10, Reach 5 ft., one target. Hit: 14 (3d6+4) slashing damage plus 10 (3d6) necrotic damage. If the target is a creature, it is cursed. While cursed, the target can't regain Hit Points, it gains no benefit from finishing a Long Rest, and its Hit Point maximum decreases by 10 (3d6) every 24 hours that elapse. A creature dies and turns to dust if reduced to 0 Hit Points by this attack.

Eldritch Blast. Ranged Spell Attack: +12, Reach 120 ft., one target. Hit: 11 (1d10+6) force damage.
Once on each of his turns when Absalom hit a creature with his eldritch blast, he can reduce that creature's speed by 10 feet until the end of his next turn. Once on each of his turns when Absalom hit a creature with his eldritch blast, he can move that creature in a straight line 10 feet closer to himself.

Spirit Siphon (Recharge 4-6). One creature cursed by Absalom within 120 feet of him that he can see must succeed on a DC 20 Constitution saving throw, taking 13 (3d8) cold damage plus 13 (3d8) necrotic damage, and Absalom or an ally within 30 feet of him regains 10 (3d6) hit points

Swirling Breath (Recharge 6). Absalom exhales shadowy fire in a 30-foot cone. Each creature in that area must make a DC 20 Dexterity saving throw. On a failed save, the creature takes 31 (7d8) fire damage plus 31 (7d8) necrotic damage and Absalom pushes them 15 feet away from him, or half as much damage and the target isn’t pushed on a successful one.

Voice of Tyranny (6/Day). Absalom casts Command as a bonus action without expending a spellslot.

Break the Oathbreaker. When a creature cursed by Absalom ends its turn further than 5 feet away from him, he can use his reaction to deal 17 (5d6) necrotic damage to that creature, in addition, attack rolls agains the target are made with advantage until the end of its next turn.

Legendary Action Uses: 3. Immediately after another creature's turn, Absalom can expend a use to take one of the following actions. Absalom regains all expended uses at the start of each of his turns.

Attack. Absalom makes an attack with his Bastard Sword.

Cantrip. Absalom casts a cantrip.

Dread Wings. Absalom magically teleports, along with any equipment he is wearing and carrying, up to 60 feet to an unoccupied space he can see that is adjacent to a creature he's cursed.
He gains a fly speed equal to his walking speed until the end of his next turn.

Dreadful Gaze (Costs 2 Actions). Absalom fixes his gaze on one creature he can see within 10 feet of him. The target must succeed on a DC 20 Wisdom saving throw against this magic or become frightened for 1 minute. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to Absalom's gaze for the next 24 hours.

Overshadowing Oath (Costs 2 Actions). Absalom may force a creature he can see within 60 feet of him to make a DC 20 Charisma saving throw or be cursed, as though they'd been hit by his rotting claws.