Blackskull, Shadow Dracolich

Legendary Resistance (3/day). If Blackskull fails a saving throw, he can choose to succeed instead.

Living Shadow. While in dim light or darkness, Blackskull has resistance to damage that isn't force, psychic, or radiant.

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

Shadow Sight. Magical darkness doesn't impede Blackskull's darkvision.

Shadow Stealth. While in dim light or darkness, Blackskull can take the Hide action as a bonus action.

Sunlight Sensitivity. While in sunlight, Blackskull has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.

Turn Immunity. Blackskull is immune to effects that turn undead.

Multiattack. Blackskull can use his Frightful Presence. He then makes three attacks: one with his bite and two with his claws.

Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 20 (2d10 + 10) piercing damage plus 11 (2d10) necrotic damage.

Claw. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 17 (2d6 + 10) slashing damage. 

Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage. 

Frightful Presence. Each creature of Blackskull's choice that is within 120 feet of Blackskull and aware of him must succeed on a DC 22 Wisdom saving throw or become frightened for 1 minute. 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 Blackskull's Frightful Presence for the next 24 hours.

Shadow Breath (Recharge 5-6). Blackskull exhales deadly shadow in a 90-foot cone. Each creature in that area must make a DC 24 Constitution saving throw, taking 93 (17d10) necrotic damage on a failed save, or half as much damage on a successful one. A humanoid reduced to 0 hit points by this damage dies, and an undead shadow rises from its corpse and acts immediately after Blackskull in the initiative count. The shadow is under Blackskull's control.

Blackskull can take 3 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. Blackskull regains spent legendary actions at the start of his turn.

Detect. Blackskull makes a Wisdom (Perception) check.

Tail Attack. Blackskull makes a tail attack.

Wing Attack (Costs 2 Actions). Blackskull beats his tattered wings. Each creature within 15 feet of Blackskull must succeed on a DC 26 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. After beating his wings this way, Blackskull can fly up to half his flying speed.