The Iron-Scale Behemoth

Ecology
The Iron-Scale Behemoth is a horrific result of the "Architect's" experiments—a massive kobold who has been mutated by raw Aether and permanently fused into a suit of stolen, heavy dwarven mining armor. It is a living tank, serving as the Scale-Syndicate's primary enforcer in the deep tunnels of Steamfort.
Combat Mechanics
The Behemoth uses a heavy, steam-powered hammer for melee attacks and a "Tail-Swipe" that can knock back multiple enemies in a 10-foot arc. It can vent a cloud of toxic, soot-filled gas from its suit's cooling pipes as a bonus action, heavily obscuring the area and poisoning creatures. It has a high damage threshold and is resistant to fire and bludgeoning damage.
Loot
The armor plates can be salvaged for "Mutated Dragon-Scales," a rare material that can be used to create leather or scale armor that provides resistance to force and poison damage.