Colossal Bone Golem

Legendary Resistance. (4/Day) If the Colossal Bone Golem fails a saving throw, it can choose to succeed instead

Regeneration. The Colossal Bone Golem regains 15 hit points at the start of its turn if it has at least 1 hit point and has enough corpses around it to help regenerate. If the Colossal Bone Golem takes radiant damage or or there are no corpses nearby, this trait doesn’t function at the start of the it’s next turn.

Multi attack. The Colossal Bone Golem can make two melee attacks: One with it's claw and one with it's fist.

Fist. Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 17 (1d10 + 9) bludgeoning damage. 

Claw. Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 23 (2d8 + 9) slashing damage. 

Wails of Woe. The dozens of mouths from the corpses that make up the Colossal Bone Golem collectively scream and wail in pain causing damage to those unfortunate enough to hear it. Creatures within 60ft of the Colossal Bone Golem must make a Wisdom Saving Throw (DC 16) and take 4d8 + 4 (32) psychic damage on a fail or half as much on a success. 

Frightful Presence. Each creature of the Colossal Bone Golem's choice that is within 60 feet of it and aware of it must succeed on a DC 16 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 the Colossal Bone Golem's Frightful Presence for the next 24 hours.

The Colossal Bone Golem can take 4 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. The Colossal Bone Golem regains spent legendary actions at the start of its turn.

Claw. The Colossal Bone Golem makes a claw attack. 

Bone Throw (Costs 2 Actions).  The Colossal Bone Golem can make a ranged attack by taking one of the many corpses that make up its body and throw it at a target within range. Using this ability does 1d6 slashing damage to the Colossal Bone Golem as a result. Ranged Weapon Attack: +9 to hit, range 60/120 ft., 1 target. Hit: 16 (2d8 + 9) bludgeoning damage.