The completed three-piece artifact — a winding box and two watches — that opens a huge portal and summons a banished feral god from the Nothing.
With the third piece — the Mysterious Watch looted from Henrik — Carl finally completes the Gate of the Feral Gods. Experimenting earlier, he and Katia Grim learned the watch placed in the box drifts to a specific time that encodes a location's coordinates (a 'reverse compass' keyed to distance from sea level), letting them dial destinations. Fully assembled — first watch in the first slot, second watch dialed, lid closed, winding mechanism turned — it flashes 'Quest Complete: The Gate of the Feral Gods' and rips open a twenty-foot swirling portal that instantly sucks its users through, dragging a wall of pressurized seawater with it (enough to topple Pandinus's wall and skewer a pazuzu's door).
Using it earns 'Who Let the Gods Out?' — opening a gate looses a banished feral god (Emberus) into the realm, drawing the wrath of the other gods. It is exactly the reckless act the game engineered Carl into performing.
A winding box paired with two ornate watches; when triggered, a twenty-foot swirling portal of light.
The floor's central artifact — a location-dialing teleport gate whose use summons a feral god.