Villbrandur the Dullahan

Warrior Spirit Summoning (Recharges after a Short or Long Rest). If the Vilbrandur is reduced to 0 hit points, he doesn’t die or fall unconscious. Instead, he regains 97 hit points. In addition, he summons three Shadows, in unoccupied spaces within 5 feet of him. The Shadows are under the Vilbrandur’s control and act immediately after him in the initiative order. Additionally, the Vilbrandur can now use the options in the “Mythic Actions” section. Award a party an additional 5,900 XP (11,800 XP total) for defeating Vilbrandur after it uses Warrior Spirit Summoning.

Unusual Nature. The dullahan doesn’t require air, food, drink, or sleep.

Turn Immunity.  Vilbrandur the Dullahan is immune to effects that turn undead.

Denial of Death. If this creature is killed, they will reform using the body of a slain humanoid with their spirit, arising at the next dawn. If they are killed in front of their gravestone, they are forced with their own mortality, and their spirit moves on.

Multiattack. The Vilbrandur the Dullahan makes two attacks either with his Greataxe or his Mighty Throw.

Greataxe. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 8 (1d12 + 5) slashing damage, plus 11 (2d10) necrotic damage. If Vilbrandur scores a critical hit against a creature, the target must succeed on a DC 15 Constitution saving throw or Vilbrandor cuts off the target’s head. The target dies if it can’t survive without the lost head. A creature that doesn’t have or need a head, or has legendary actions, instead takes an extra 27 (6d8) slashing damage.

Mighty Throw. Ranged melee Attack: +8 to hit, range 60 ft., one target. Hit: 14 (2d12 + 5) slashing damage. His axe magically reappears back into his hand afterwards.

Vilbrandur 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. Vilbrandur regains spent legendary actions at the start of its turn.

Attack. Vilbrandur the Dullahan makes one attack.

Frightful Presence (Costs 2 Actions). Each creature of Vilbrandur's choice within 30 feet of it must succeed on a DC 15 Wisdom saving throw or become frightened of Vilbrandur until the end of its next turn.

Head Hunt (Costs 3 Actions). The dullahan moves up to its speed without provoking opportunity attacks and makes one Greataxe attack with advantage. If the attack hits, but is not a critical hit, the attack deals an extra 27 (4d12) necrotic damage.

If the dullahan’s Headless Summoning trait is active, it can use the options below as legendary actions.

Coordinated Assault. The dullahan makes a Greataxe attack, and then one Shadow Vilbrandur can see within 30 feet of it can use its reaction to make a melee attack.

Headless Wail (Costs 2 Actions). An echoing shriek issues from Vilbrandur's headless stump. Each creature of Vilbrandur the Dullahan’s choice within 10 feet of it must make a DC 15 Intelligence saving throw. Each creature takes 16 (3d10) psychic damage on a failed save, or half as much damage on a successful one. If one or more creatures fail the saving throw, Vilbrandur gains 10 temporary hit points.