Runic Colossus

Gargantuan construct, unaligned

Armor Class

20 (natural armor)

Hit Points

315 (18d20 + 126)

Speed

60 ft.

Damage Resistances

acid, cold, fire, lightning

Damage Immunities

poison, psychic; bludgeoning, piercing, and slashing from nonmagical attacks

Condition Immunities

charmed, exhaustion, frightened, paralyzed, petrified, poisoned

Senses

darkvision 120 ft.

Languages

understands Giant but can't speak

Challenge

21

Proficiency Bonus

+7

Immutable Form

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

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.

Actions

Multiattack

The colossus makes two Slam attacks and then uses Stomp.

Slam

Melee Weapon Attack: +14 to hit, reach 20 ft., one target. Hit: 26 (3d12 + 7) bludgeoning damage.

Stomp

Melee Weapon Attack: +14 to hit, reach 20 ft., one target. Hit: 29 (4d10 + 7) bludgeoning damage. If the target is a Huge or smaller creature, it must succeed on a DC 22 Dexterity saving throw or have the prone condition. Until the colossus uses its Stomp again or moves, the creature has the restrained condition. The restrained creature or another creature within 5 feet of it can use its action to make a DC 22 Strength check. On a successful check, the affected creature relocates to an unoccupied space of its choice within 5 feet of the colossus and is no longer restrained.

Arcane Beam (Recharge 5-6)

The colossus fires a beam of magical force from its chest, hands, or head in a 150-foot line that is 10 feet wide. Each creature in that area must make a DC 22 Dexterity saving throw, taking 58 (9d12) force damage on a failed save, or half as much damage on a successful one.