E1M8: Deathedral (Strange Aeons)

E1M8: Deathedral is the first boss map of Strange Aeons, designed by Impie in 2015 and constructed in Doom Builder 2.

Essentials
The player's goal is the switch-operated spider door to the left of the altar, which requires all three keys.

On the altar ahead are three pressure plates. The center plate causes the door on the right to open into a cross-shaped corridor, which connects the church with its three dungeons. The other two pressure plates open the doors in the left and right branches of the corridor. All three doors eventually close after a time, and can only be operated by pressure plates, which are guarded by a Death Incarnate in each dungeon.

The yellow skull key is on a pillar in the crypt, across the corridor from the church. A switch lowers it for the player, but Men from Leng will teleport into the area.

The red skull key is in a room full of pillars beyond the right door. The switch at the back of the room is a trap that summons more Men from Leng; the switch that actually lowers the key is in back of one of the many pillars.

The blue skull key is beyond the left door. The pillar's switch is hidden in a small, dark sewer tunnel: when the player enters this tunnel, four Glaaki Spawn are unleashed upon him. When this key is grabbed, a pair of Demon Wizards will be waiting for the player in the church.

Once you have all three keys, open the spider door and jump through the portal. You will travel to yet another dimension -- the Land That Time Forgot of Episode 3 -- and appear in a small pillar arena with 1 to 3 Shadow Beasts. When all Shadow Beasts on the level are slain, a switch and Soul Sphere are revealed on either end of the arena. The switch lowers the lift to the exit slipgate.

Boss: Shadow Beast
The Shadow Beast is big and tough, and gets more aggressive the more damage it takes. It has a variety of highly damaging attacks at its disposal, though it is initially so docile that it's practically harmless. Its most dangerous feature is that it randomly explodes into a shower of hungry wraiths when damaged, then respawns in an unpredictable location moments later.

The easiest way to deal with them is to stand on the far sides of the arena, across the blood canals, and pick them off from afar. This may allow them (or their wraiths) to corner you, however.

Secrets
"Use" the beating heart on the altar to lower two pillars in the church, revealing a pair of Soul Spheres and Death Incarnates.

Open the center and right pressure plate doors, then run straight ahead to the crypt. A sarcophagus to your right has opened, revealing a cache of energy cells and other goodies.

Inspiration and development
Impie tested the Shadow Beast battle using the sinking floor area of Ultimate Doom's E2M6. He modeled the final arena on the same location.