Urkanthos

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

Magic Resistance. Urkanthos has Advantage on saving throws against spells and other magical effects.

Blood rush. if Urkanthos kills a creature, he regain the amout of hit points that he just dealt to said creature.

Multiattack. urkanthos makes 2 attacks.

Blood for the Blood God. Melee Attack Roll: +11, reach 5 ft. Hit: 8 (1d6 + 5) magical bludgeoning, and the amount of damage Urkanthos deals is added to his next hit resets on short rest, or long rest which ever comes first.

Spellcasting. Urkanthos the following spell, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 18):

At Will: Hellfire

Parry. Trigger: Urkanthos is hit by a melee attack roll. Response: Urkanthos adds 6 to its AC against that attack, possibly causing it to miss.

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

Dread Authority. Urkanthos uses Spellcasting to cast Hellfire. Urkanthos  can’t take this action again until the start of its next turn.

Blood theif. Constitution Saving Throw: DC 18, one creature Urkanthos can see within 120 feet. Failure: 17 (5d6) Necrotic damage, and the target’s Hit Point maximum decreases by an amount equal to the damage taken. Failure or Success: The death knight can’t take this action again until the start of its next turn.

Lunge. Urkanthos moves up to half its Speed, and it makes one Blood for the Blood Gods attack.