Immutable Form. The colossus is immune to any spell or effect that would alter its form.

Sled Knees. The colossus ignores difficult terrain, and may deal 4d10 bludgeoning damage to any structures it ends its movement next to. 

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

Siege Monster. The colossus deals double damage to objects and structures.

Tectonic Steps. Any enemy outside the colossus that starts its turn within 30 feet of it must succeed on a DC 22 Strength saving throw or be knocked prone until the start of the enemy’s next turn.

Multiattack. The colossus makes three attacks — one with its slam and two with its eldritch turrets — and then uses Stomp.

Slam. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 29 (2d12 + 10) bludgeoning damage, and the colossus can push the target up to 20 feet away from it.

ZroTurret. Ranged Spell Attack: +18 to hit, range 300 ft., one target. Hit: 18 (2d8) force damage, and if the target is a creature, it is knocked prone.

Zro Wave. The colossus stomps one of its feet at a point on the ground within 20 feet of it, releasing a terrifying wave of psionic force. Any creature in a 20-foot-radius, 20-foot-high cylinder centered on this point must succeed on a DC 26 Dexterity saving throw or take 33 (4d10) psychic damage and fall prone. Until the colossus uses its Zro Wave again or moves, the creature is paralyzed. While restrained in this way, the creature (or another creature within 5 feet of it) can use its action to make a DC 22 Intelligence check. On a success, the creature is no longer paralyzed.

Structures, as well as nonmagical objects that are neither being worn nor carried, take the same amount of damage in magical bludgeoning if they are in the cylinder (no save).

Incinerating Beam (Recharge 5–6). The colossus fires a beam of light in a 150-foot line that is 10 feet wide. Each creature in the line must make a DC 22 Dexterity saving throw, taking 60 (8d10) radiant damage on a failed save, or half as much damage on a successful one. A creature reduced to 0 hit points by this beam is disintegrated, leaving behind anything it was wearing or carrying.