Acheron Ravenite, The Imperator-Rex

Legendary Resistance (1/Short Rest). When Acheron fails a saving throw, he can choose to succeed instead.

Action Surge (2/Short Rest). Once per turn, Acheron can take an additional action and bonus action on his turn.

Arcane Shaping. When Acheron casts a spell that causes damage or that forces other creatures to make a saving throw, he can choose himself and any number of allies to be immune to the damage caused by the spell and to succeed on the required saving throw.

Imperator's Will. Acheron has advantage on saving throws against spells and other magical effects, as well as any effect that would cause him to be unwillingly Incapacitated, Paralyzed, Restrained, Stunned, or Unconscious. In addition, any critical hit against him becomes a normal hit.

Vorpal Warrior. When Acheron rolls damage dice for any damage he deals with an attack or spell, he can roll one additional damage dice for each 1 or 2 rolled, including on any additional damage dice rolled as a result of this trait, up to a maximum of 6 additional dice.

Warcrown of the Ravenite. Acheron wears the Warcrown of the Ravenite's, and it cannot be removed from his person unless he is reduced to 0 Hit Points or dies. While wearing the crown, he gains the effects of the Mind Blank spell when he finishes a long rest, and his Wisdom score increases from 13 to 17, and his Charisma score from 15 to 17 (included in his statistics).

Multiattack. Acheron makes three attacks, using Dominion, Enervating Bolt, and Psionic Lance in any combination. He can replace two of his attacks with a use of his Psionics or Spellcasting.

Dominion. Melee or Ranged Attack Roll: +14 to hit, reach 5 ft., or range 10/30 ft. one target. Hit: 13 (1d10 + 8) Slashing damage plus 11 (3d6) Force damage. If the target is a Humanoid, it must expend and roll one of its Hit Dice, taking Necrotic damage equal to twice the amount rolled. Acheron regains Hit Points equal to the Necrotic damage dealt. If this Necrotic damage reduces the target to 0 Hit Points, or if the target has no remaining Hit Dice, it immediately dies and a Shadow under Acheron's control rises from its corpse. The Shadow shares Acheron's initiative but acts immediately after him in combat, and remains until the next dawn. If the attack roll had advantage, Acheron scores a critical hit on a roll of 17+ on the d20. The sword magically returns to Acheron's hand or hovers within 5 feet of him immediately after a ranged attack, and he can't be disarmed of it.

Enervating Bolt. Ranged Attack Roll: +10 to hit, range 120 ft., one target. Hit: 17 (3d8 + 4) Necrotic damage, and the target can't regain Hit Points until the end of its next turn.

Psionic Lance. Melee or Ranged Attack Roll: +10 to hit, reach 5 ft., or range 60 ft., one target. Hit: 18 (4d6 + 4) Force damage. If the target is Huge or smaller, it is also pushed 10 feet in a direction of Acheron's choice and knocked Prone.

Psionics. Acheron casts one of the following spells, requiring no components and using Intelligence as the spellcasting ability (+10 to hit with spell attacks, spell save DC 18):

At Will: Gravity Sinkhole, Hold Person (level 3 version), Magic Missile (level 3 version)

2/Day Each: Dimension Door, Slow, Synaptic Static

1/Day Each: Disintegrate, Hold Monster (level 6 version), Reverse Gravity

Spellcasting. Acheron casts one of the following spells, requiring no Material components and using Intelligence as the spellcasting ability (+10 to hit with spell attacks, spell save DC 18):

2/Day Each: Circle of Death, Death Ward, Harm, Ray of Sickness (level 5 version), Revivify

Psionic Step. Acheron teleports to an unoccupied space he can see within 10 feet.

Imperial Rally (2/Short Rest). Acheron regains 14 (3d6 + 4) Hit Points and gains the same number of Temporary Hit Points. Each creature of Acheron's choice that he can see within 30 feet of himself also gains these Temprory Hit Points.

Acheron can take two reactions on each round in combat, but only one per turn.

Imperial Retort. When Acheron is hit by an attack or fails a saving throw, he adds 4 to his AC against the triggering attack or to his save's total, potentially causing the attack to miss or save to succeed. If this causes the attack to miss or save to succeed, he can teleport to an unoccupied space he can see within 10 feet and make one attack using Dominion, Enervating Bolt, or Psionic Lance.

Psionic Shield (2/Short Rest). When Acheron is hit by an attack or fails a saving throw, he fortifies his body and mind with psionic energy, and until the end of his next turn he has a +4 bonus to his AC and any saving throws he makes, potentially causing the triggering attack to miss or save to succeed. While Acheron has this bonus, he has immunity to Force damage.

Acheron can take 2 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. Acheron regains spent legendary actions at the start of his turn.

Attack (1 Action). Acheron makes one attack using Dominion, Enervating Bolt, or Psionic Lance.

Psionic Jaunt (1 Action). Acheron moves up to his speed without provoking opportunity attacks, and during this movement he can move through other creatures and objects as if they were difficuly terrain. If Acheron ends his turn in the same space as another creature or an object, he is shunted to his last occupied space, and both Acheron and the creature or object take 10 (3d6) Force damage.

Imperial Arcanum (2 Actions). Acheron uses his Psionics or Spellcasting.