Xerfilstyx

Fear aura. Each creature within 30ft of the xerfilstyx must make a DC 16 Charisma saving throw or be frightened whilst within the aura. 

Blood drain. When the xerfilstyx hits with a tail attack as a bonus action it can drain 1d12 hit points and stores them up max of 20d12. 

Devil’s Sight. Magical darkness doesn’t impede the devil’s darkvision.

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

Magic Weapons. The xerfilstyx's weapon attacks are magical.

Toss. After dashing as a bonus action the xerfilstyx can make an apposed strength check to throw a creature 25ft in any direction of their choice if they succeed. 

Knowledgeable. The xerfilstyx is immune to the effects of the river styx and gains memories of creatures who have touched the waters meaning it gains advantage on all religion, history and intelligence checks. 

Regeneration. The xerfilstyx regains 5 hit points at the start of its turn. If the xerfilstyx takes radiant damage, this trait doesn’t function at the start of the xerfilstyx’s next turn. The xerfilstyx dies only if it starts its turn with 0 hit points and doesn’t regenerate.

Innate Spellcasting. The xerfilstyx’s innate spellcasting ability is Charisma (DC 17). It can innately cast the following spells, requiring no material components:

• At will: charm person, cone of cold, confusion, detect good and evil, detect magic, dispel magic, hold person, ice storm, legend lore, magic circle, major image, suggestion, telekinesis, wall of ice
• 3/day: symbol
• 1/day: foresight

Multi attack. The xerfilstyx makes two claw attacks, one bite attack, one tail and also one horn attack. 

Claws. Melee Weapon Attack: +10 to hit, reach 10 ft., 1 target. Hit: 13 (3d4 + 6) slashing damage. 

Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., 1 target. Hit: 15 (2d8 + 6) piercing damage. 

Tail. Melee Weapon Attack: +10 to hit, reach 5 ft., 1 target. Hit: 17 (2d10 + 6) bludgeoning damage and the xerfilstyx can make a grapple check and if the target is still grappled by the start of their next turn the target is subjected to the blood draining ability until they break free with an apposed strength check. (during this the target is in the same square as the xerfilstyx). 

Horn. Melee Weapon Attack: +10 to hit, reach 10 ft., 1 target. Hit: 16 (3d6 + 6) bludgeoning damage. 

Styx breath. The xerfilstyx spews a 50ft cone of scalding blood mixed with the water of the river styx and each creature within the range must make a DC 17 Dexterity saving throw or take psychic damage equal to the amount of d12s drained from creatures from the blood drain effect within the past hour, on a successful save a creature takes half damage.