An intricate system of sewers and dungeons that spreads out below Leyndell, Royal Capital. It is crawling with all kinds of shunned creatures, most notably the Omen, who are imprisoned there unbeknownst to anyone. The layout is disorienting due to the multitude of tunnels, waterways, and chambers. Deep within the dungeon is a cathedral, where an encounter with Mohg, the Omen occurs. The altar at the back of the cathedral is illusory, and hides a passage which can only be unsealed by killing Morgott, the Omen King in the city above. The passage leads to a catacomb which plunges deep into the earth. It is here that a nomadic tribe was once entombed so as to bury a maddening disease that followed them, and where, in their despair, they summoned the flame of frenzy. The Three Fingers can be met behind a door at the lowest level of the catacomb, provided one removes all of their equipment first.

The entrance to the Leyndell Catacombs can be found within the Subterranean Shunning-Grounds. It is in the room with the Crayfish.