Chardalyn Guardian

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

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

Construct Nature. The guardian doesn't require air, food, drink, or sleep.

Multiattack. The guardian makes three slam attacks or two chardalyn sword attacks. 

Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 4) bludgeoning damage.

Chadalyn Sword. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 21 (3d10 + 4) slashing damage.

Chardalyn Spike Volley (Recharge 5–6). The guardian releases a volley of sharp Chadalyn spikes in a 15-foot cone. Each creature in that area must make a DC 14 Dexterity saving throw, taking 28 (8d6) piercing damage on a failed save, or half as much on a successful one.

Chardalyn Breath (Recharge 6). The guardian exhales a blast of harmful Chardalyn particles in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking 49 (14d6) poison damage on a failed save, or half as much on a successful one. Additionally, a creature that fails its save is poisoned for 1 minute. The poisoned creature can repeat the saving throw at the end of each of its turns, ending the poison on a success.