Vaanor

Innate Spellcasting. Vaanor's innate spellcasting ability is Wisdom (spell save DC 22, +14 to hit with spell attacks). Vaanor can innately cast the following spells, requiring no material components:

At will: hellish rebuke (as a 3rd-level spell), locate creature, locate object 

3/day each: hold monster, hold person (as a 5th-level spell), hunter's mark

1/day: forcecage 

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

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

Soul Sentry. Vaanor's weapon attack are magical. When Vaanor hits an undead with a weapon attack, the target takes an extra 7 (2d6) force damage.

Sure-Footed. Vaanor has advantage on Strength and Dexterity saving throws made against effects that would knock it prone.

Three Heads. Vaanor has advantage on Wisdom (Perception) checks, as well as Constitution saving throws to maintain concentration on spells.

Wakeful. When one of Vaanor's heads is asleep, its other heads are awake. In addition, magic can't put it to sleep.

Multiattack. Vaanor can use its Inescapable Presence. It then makes three bite attacks.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 16 (3d6 + 6) piercing damage plus 7 (2d6) fire damage. If this is the first attack Vaanor has made as part of its Multiattack, the target must succeed on a DC 20 Strength saving throw or be knocked prone. If this is the second attack, the target must succeed on a DC 20 Constitution saving throw or be stunned until the start of Vaanor's next turn. If it is the third attack, the target must succeed on a DC 20 Wisdom saving throw or be paralyzed until the start of Vaanor's next turn.

Inescapable Presence. Vaanor magically restricts one creature it can see within 120 feet of it from fleeing. The target must succeed on a DC 22 Wisdom saving throw or become unable to move or teleport away from Vaanor for 1 minute. Creatures that can't be frightened are immune to this effect. 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 is immune to Vaanor's Inescapable Presence for the next 24 hours.

Hellfire Breath (Recharge 5-6). Vaanor exhales a debilitating fire in a 90 foot cone. each creature in that area must make a DC 20 Dexterity saving throw, taking 35 (10d6) fire damage and 35 (10d6) psychic damage on a failed save or half as much on a successful one.

Summon Hounds (1/Day). Vaanor magically summons 4d4 hell hounds. A summoned hell hound appears in an unoccupied space within 60 feet of Vaanor and acts as Vaanor's ally. It remains for 1 minute, until it or Vaanor dies, or until Vaanor dismisses it as an action.

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

Bit. Vaanor makes one bite attack.

Move. Vaanor moves up to its speed.

Trailblaze (Costs 2 Actions). Vaanor moves up to twice its speed, leaving a trail of fire in its wake. During this movement, Vaanor doesn't provoke opportunity attacks, and it can move through the space of any creature that is Huge or smaller. Each creature in its path must make a DC 20 Dexterity saving throw, taking 15 (2d8 + 6) bludgeoning damage and 22 (5d8) fire damage on a failed saved, or half as much damage on a successful one. Until the end of Vaanor's next turn, each space it moved through is filled with an opaque, 20-foot-high wall of fire. Whenever a creature enters the wall for the first time on a turn of ends its turn there, it takes 22 (5d8) fire damage.

Release the Hounds (Costs 3 Actions). Vaanor uses its Summon Hounds action, even if ithas already used it once that day.