Evasion. If the skull lord is subjected to an effect that allows it to make a Dexterity saving throw to take only half the damage, the skull lord instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.
Legendary Resistance (3/Day). If the skull lord fails a saving throw, it can choose to succeed instead.
Master of the Grave. While within 30 feet of the skull lord, any undead ally of the skull lord makes saving throws with advantage, and that ally regains 1d6 hit points whenever it starts its turn there.
Multiattack. The skull lord makes three bone staff attacks.
Bone Staff. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage plus 14 (4d6) necrotic damage.
The skull lord 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. The skull lord regains spent legendary actions at the start of its turn.
Bone Staff (Costs 2 Actions). The skull lord makes a bone staff attack.
Cantrip. The skull lord casts a cantrip.
Move. The skull lord moves up to its speed without provoking opportunity attacks.
Summon Undead (Costs 3 Actions). Up to five skeletons or zombies appear in unoccupied spaces within 30 feet of the skull lord and remain until destroyed. Undead summoned in this way roll initiative and act in the next available turn. The skull lord can have up to five undead summoned by this ability at a time.