Legendary Resistance (3/Day). If the Rusted fails a saving throw, it can choose to succeed instead.

Multiattack. The Rusted makes two Bite attacks.

Bite. Melee Attack Roll: +12, reach 20 ft. Hit:29 (4d10 + 7) Piercing damage.

Steam Breath (Recharge 5–6). Dexterity Saving Throw: DC 19, each creature and flammable object that isn't being worn or carried in a 60-foot Cone. Failure: 45 (7d12) Fire damage, and the target starts burning. Success: Half damage only. Failure or Success: Being underwater doesn't grant Resistance to this Fire damage.

Encasing Rust. Constitution Saving Throw: DC 19, one creature within 20 feet of the Rusted. Failure: 14 (4d6) Poison damage, and the target has the Poisoned condition until the end of its next turn. While Poisoned, the target has the Paralyzed condition.