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

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

Magic Weapons. Ulamog's weapon attacks are magical.

Innate Spellcasting. Ulamog's innate spellcasting ability is Charisma (spell save DC 23, +15 to hit with spell attacks). It can innately cast the following spells, requiring no material components:

At will: greater restoration, pass without trace, water breathing, water walk

1/day each: commune, dispel evil and good, earthquake, fire storm, plane shift (self only)

Maul. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit:31 (6d6 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 15 Constitution saving throw or be stunned until the end of Ulamog's next turn.

Bolt. Ranged Spell Attack: +15 to hit, range 600 ft., one target. Hit:24 (7d6) damage of one of the following types (empyrean's choice): acid, cold, fire, force, lightning, radiant, or thunder.

Attack. Ulamog makes one attack.

Bolster. Ulamog bolsters all nonhostile creatures within 120 feet of it until the end of its next turn. Bolstered creatures can't be charmed or frightened, and they gain advantage on ability checks and saving throws until the end of the empyrean's next turn.

Trembling Strike (Costs 2 Actions). Ulamog strikes the ground with its maul, triggering an earth tremor. All other creatures on the ground within 60 feet of the empyrean must succeed on a DC 25 Strength saving throw or be knocked prone.