E3M7: The Chasm (Heretic)

E3M7: The Chasm is the seventh level in The Dome of D'Sparil episode of Heretic.

Yellow key
You'll start this level in a small and damp room, with ophidians hidden in some sort of cells to your right and left. Run to the stairs and go up to reach a room filled with golems. Be careful to the mages and the Iron Lich(es) to the east, which you can easily kill now if you've got enough ammo.

Grabbing the bag of holding to the west will darken the room and open three doors with some monsters. Open the  the door, go down and let the yellow door to your right. Then climb the stair and follow the path until you meet with another door. Open it and you'll enter a room on the opposite side of the last one with an unreachable stair to the left. Go straight to the end and press the switch : it'll lower the stair but also reveal a room with axe throwers inside. Fight on your way back to the stair, then go up and take the yellow key.

Return to the yellow door and unlock it.

Green key
If you haven't killed any monster in this central hall before, there's an interesting fight here. Deal with them then reach the upper hallway to the south. Saberclaws await you there, with ophidians hiding on two platforms. Once defeated turn south and press the switch to the west. Be careful as ophidians are lurking in the shadows right before you can reach the switch.

A wall will rise to the south, revealing a narrow stair which will lead you to a small room uplooking some teleporters. Entering this room to hit the switch will awake a molotaur. Fight it or leave it but then be aware that you'll have to avoid it again in the upper hallway.

Go back to the upper hallway and open the door to the right of the green door. You're now in the teleporter room, with the green key to your left, unreachable for now. Take the two teleporters and press the two switches (they'll lead you to the platforms where you saw ophidians : by jumping from there to the north you can take some ammo and put your hands on some vials) then come back and you'll notice a third teleporter has appeared. Taking it will transport you to the green key.

Run back to the green door and descend to a large cave.

Blue key
You'll have to fight weredragons and saberclaws to reach a passage on the west side of the cave. Enter the corridor, and proceed to the end. Before engaging on the bridge, try to kill all the demons which will fly to you and which would lower your progress.

The bridge is windy, and ifg you fall to the west side, you'll have to run to a teleporter pod on which you'll find an ethereal shield. If you run to the end of the bridge you'll grab the blue key.

You can return to the central hall by the cave where some saberclaws will attack you, then by the upper hallway, to open the blue door.

Map exit
The exit is right behind the blue key door, but note that there will be the Iron Lich(es) there if you didn't wipe the out before from outside.

Press the switch and onto the next level !

Secrets

 * 1) North of the yellow door is a room with a ledge on the north side. You can get to it from the first step to the west or east. Once on the ledge, you can open the door to the north, which reveals a switch. Hit the switch to reveal a teleporter to the west, which takes you to an energy orb and a Dragon Claw.
 * 2) To the south of green key is a secret door which reveals some Timebombs.
 * 3) The southwest teleporter is not really a teleporter; once you walk over it, it opens an area to the south with a Hellstaff.
 * 4) On the way to the windy chasm in the south part of the map is a staircase with a pool at the bottom. Just to the south of the pool is an area with a Torch to the east; just opposite the Torch is a secret door to a Phoenix Rod.
 * 5) At the south end of the chasm are a pair of Wings of Wrath and a blue key. Use the wings to fly to the west and east sides of the chasm; there are some paths there which lead to all sorts of neat stuff in the areas which look out into the chasm.
 * 6) See above secret
 * 7) After getting the blue key, a bunch of secret areas open up in the area northeast of the chasm, southeast of the green door. There is a Chaos Device...
 * 8) ...A Map scroll...
 * 9) ...A Tome of Power...
 * 10) ...And a Mystic Urn.

The following location does not count as a secret:
 * 1) Up the stairs to the east of the yellow door is a room which has a passage to the south which leads to a switch. When you hit the switch, some Undead warriors are revealed to the south. The room they're in has an opening in the southwest corner; go through this opening to get some goodies.