This level occupies the map slot E4M3. For other maps which occupy this slot, see Category:E4M3.

E4M3: Ambulatory is the third level in The Ossuary episode of Heretic Shadow of the Serpent Riders.

E4M3 heretic

Map of E4M3


(To be written)

  • The central room with four lightning-bolt walkways looks impassable at first, but just step into it and the first walkway will rise beneath you, allowing you to get the yellow key and to return.
  • The safe path through the grid of crushers is at first marked with Time Bombs of the Ancients, but as you traverse it (and collect the Bombs) the light in each safe square will go out, so the path remains marked.


  1. In the starting room is a grid of crushing ceilings. In the northwest corner of this is a secret door leading west (the light may be blinking on and off). The secret door leads to some ammo and a tome. There may be three Iron Liches back there, unless you've already killed them; they'll be behind a grating, making them easier to kill this way.
  2. The central lava pit has a hallway surrounding it. Pieces of this hallway open up gradually as the level progresses. When you enter the room with the green key, and drop into the sludge pit, the northwest portion of this central hallway is opened up. It contains a bag and some ammo. In the north part of this area is a secret door leading east and then north to a secret area with a bunch of ammo (mostly mace spheres).
  3. The south platform in green key room contains a door to a room with secret doors on either end. The doors open up when you walk into the area on the north end of the room where the Iron Liches are/were. Each door leads eventually to a staircase which leads up to an area with two crystal flasks, some ammo, a bag, and a map. There's a Maulotaur up there too.

The following locations do not count as secrets:

  1. The northeast section of the central hallway has a hidden door leading north, and another hidden door behind that to the right.
  2. When entering the exit room, go back quickly; the wall to your right will be lowered temporarily to reveal a small area. At the east end of the area is a set of secret doors on the left. Don't miss the small niche to the east of the doors.


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