Plonk: You find nothing of immense value on the warforged, just standard adventuring equipment (rapier, light crossbow, 10 bolts, a traveling cloak, some thieves' tools, and a backpack).
Rawhide: You find an odd plate in the center of the warforged's chest. Slightly larger than your head, it has a semi-spherical indent in its center, smooth to the touch and slightly grooved.
Flawed: The stairs empty out into a larger tunnel, roughly twenty feet wide, with a ten-foot wide trench cut through the middle of it to carry sewer water from the upper levels of the city through to the deeper parts of the sewers. On either side of the trench, a five-foot wide walkway is dotted with iris-shaped valves, which open at regular intervals, spouting jets of sewer water into the center trench and onto the walkways. A grate designed to look like a spider's web blocks the tunnel to the right of the bottom of the stairs.