Wy, Titan of Creation's Folly

Legendary Resistance (3/day):  If Wy should fail a saving throw, it may instead choose to succeed.

Siege Monster: Wy deals double damage to walls and structures.

Crushing Claws. Melee Weapon Attack: +10 to hit, reach 15 ft., 1 target. Hit: 6d6 + 8 bludgeoning damage. 

Heart of the Mountain. RangedWeapon Attack: +10 to hit, range 300 ft., all targets in a 10ft wide line OR all targets in a 60ft cone. Hit: 6d8 + 10) fire damage.

Wy may make 3 legendary actions but only 1 per turn. It regains 1 action at the end of its turn.

Landslide (Costs 2 Actions). Wy shakes loose boulders and rock, crushing all caught beneath it. All creatures within 20 ft take 4d8 bludgeoning damage from falling rocks. These boulders now act as part of the environment and are difficult terrain.

Billow (Costs 1 Action). Wy stokes the fire in its mountainous form, sending thick smoke billowing from its rising peaks. All creatures within 10 ft of Wy are blinded until they move out of its area of effect. All ranged attacks have disadvantage while targeting Wy while the smoke is active. The smoke dissipates at the end of Wy's next turn.

Earth Surge. Wy retracts it legs and slams down into the ground. Wy then sends shards of stone up through the earth all around it. All creatures within 30 feet must make a DC18 DEX save. On a failure, they take 4d12 piercing damage. They take half as much on a success. Wy's movement is reduced to 0 for 1 minute but it's AC is increased by 3 during this time.