Crioderian Heavy ATUM

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

Legendary Resistance (3/Day). If the Crioderian Heavy ATUM fails a saving throw for a spell, it can choose to succeed instead as well as gain another charge of Arcane Overload and Arcane Ward.

Combat Designed. The Crioderian Heavy ATUM has many different ways to be effective in combat. It can take any of the below Actions.

Multiattack. The Crioderian Heavy ATUM can make two attacks with it's Primary Cannon as well as a Magic Missile Barrage or a Flaming Eruption if either are available.

Primary Cannon. Ranged Weapon Attack: +9 to hit, reach 120 ft., 1 target. Hit: 25 (3d12 + 5) force damage. 

Magic Missile Barrage (Recharge 5–6). The Crioderian Heavy ATUM casts an empowered and altered version of Magic Missile. Each creature of it's choosing within 60 ft of it immediately takes 19 (4d6+5) force damage.

Flaming Eruption (Recharge 4–6).  The Crioderian Heavy ATUM casts an empowered version of Burning Hands. Each creature in a 30 ft cone must make a DC 18 Dexterity saving throw, taking 21 (6d6) Fire damage on a failure and half as much on a success.

Arcane Limiter Override.  The Crioderian Heavy ATUM can override it's safety limits if needed to allow it to take another Action or Movement as a bonus action. When it does so the ATUM overheats and takes 22 (4d10) Fire damage and opens the vents along it's body.

Any creatures on top of the ATUM take this damage as well as vents open up to expel this heat build up. These Vents remain open until the start of the ATUM's next turn constantly discharging this excess heat; any creatures that enter the discharging heat takes 7 (2d6) fire damage. While open these vents can be targeted. Targeting these vents gives disadvantage and they have an AC of 21. Any hits to an open vent counts as a Critical hit.

Arcane Ward (Recharges on use of Legendary Resistance). As a reaction the Crioderian Heavy ATUM may raise it's AC by 5 until the beginning of it's next turn.

Arcane Overload (Recharges on use of Legendary Resistance). The Crioderian Heavy ATUM emits a sphere of stored arcane energy from it. Each creature within 10 feet must make a DC 18 Dexterity saving throw, taking 55 (10d10) Force damage on a failed save, or half as much damage on a successful one.