Multiattack. The Rusted makes three attacks, using Slam or Rusted Shot Put in any combination.

Slam. Melee Attack Roll: +10, reach 10 ft. Hit:20 (4d6 + 6) Bludgeoning damage.

Rusted Shot Put. Ranged Attack Roll: +10, range 60/240 ft. Hit:15 (2d8 + 6) Bludgeoning damage, and the target has the Poisoned condition until the end of its next turn.

Rust-Riddled Hide. Trigger: The Rusted is hit by an attack roll that deals Bludgeoning, Piercing, or Slashing damage. Response—Constitution Saving Throw: DC 16, each creature of the Rusted's choice in a 5-foot Emanation originating from the Rusted. Failure: the target has the Poisoned condition until the end of the target's next turn.