E4M7: Ramparts of Perdition (Heretic)

E4M7: Ramparts of Perdition is the seventh level in The Ossuary episode of Heretic Shadow of the Serpent Riders.

Essentials
You will begin in a chamber which is open in the back, so while there are no immediate attacks it is not a good idea to linger. Instead of going forward, go through the window to your right where you can find a spiral staircase upwards, with some handy supplies. At the top, the black iron paneling is a door which you can go through and then drop down to where you would have arrived going forward from the start. Approach the angled edge of this region to lower a lift to a platform with the Ethereal Crossbow. So equipped, you're now in a good position to explore the open castle roof area. You can find Gauntlets of the Necromancer on the gibbet. Exploring around the edges of this area will yield some ammo and items, but be careful about falling from the ledge as you'll have to slog over lava if you drop down (if you do fall, the escape teleporter is on the south side of the central castle, or through a secret wall to the north of the level).

The switch on the back side of one of the gray pillars raises the bridge which allows you safe access back and forth between the rooftop and the chapel area. The other switches in the rooftop area are all related to creating an access path to the optional hellstaff across the black platforms to the north. Now head to the eastern twin of the room you started in, go through the window and across the bridge to reach a chapel area. There are a few paths to explore here but to progress, head straight forward. When you see the yellow door, approach it even though you don't have the key yet. A teleport chamber will open behind you, giving you access to a new area south of the lava lake.

After teleporting, head downstairs to a green shrine with a horse motif, where you'll find the yellow key on an elevated platform. Walking into the water pool at the center of the room will lower a lift, which you can ride up to get to the yellow key platform. Note that the first time stepping onto this lift triggers one-time access to a secret so be careful if you're aiming for max score. Get the secret if you want it, then use the lift to dash onto the platform to the silver shield. The yellow key will be revealed and you can take a second ride on the platform to dash to it as well. Taking the key triggers a disciple ambush. Once you have the key, you can head back up and cross a bridge that's risen to the main castle roof, then head back to the yellow door.

Even though you don't have the key yet, approach the blue door. As you get close, the walls drop, rearranging the room to release monsters and open the way to new areas. Escape and head back towards the bridge to the intersection room and through the south door to the green key shrine. The key has been lowered now and can be collected. With the green key, head back to the areas that opened when you approached the blue door, where you'll find a teleport to the west side of the map.

Having taken the teleport to the green door area, go through either of the doors to the large phoenix room. You can find a Phoenix Rod on the big red phoenix emblem, but be careful, it hurts to stand there. Pulling the switch on the upper balcony lowers a pair of lifts that will get you to the blue key. This key is also rigged with a trap: an ambush of a few measly gargoyles and fire gargoyles. With the key, teleport back to the blue door area and head through the blue door. You'll find a large room here with a switch high above and some windows leading to another outdoor lava area. There are some switches down there visible from the window, hinting that you'll want to go down there to pull them, but beware, there's both damaging lava and iron liches below. Pulling the switches will give you an access back up to the switch that you couldn't reach. Pulling it opens areas down below containing even more monsters and the exit.

Secrets

 * 1) From the starting castle, run off into the lava pit in the northwest direction to where there's a small ledge with a crystal vial.  The wall right behind this ledge is pass-through leading you to a secret chamber with a Morph Ovum and a teleport that takes you to the gibbet. (sector 55)
 * 2) In the yellow key room, step onto the lift, then immediately cross over to the matching lift that lowers when you do so.  Ride it up to a secret containing a Ring of Invulnerability.  If missed, the access to this secret cannot be re-triggered. (sector 151)
 * 3) In the chapel stained glass room, dash from the balcony into the alcove of the D'Sparil window.  It opens, and entering grants access a secret chamber containing disciples and a Tome of Power behind you. (sector 265)
 * 4) When collecting the green key, doors temporarily open across the room to either side of the horsemen panel, leading to a small chamber containing a Chaos Device.  This can be re-triggered as desired.  Collecting the Chaos Device triggers a small ambush outside. (sector 328)
 * 5) After collecting the yellow key, investigate the northern alcove that opened below.  The unusually large green block marks a secret door leading to a Map Scroll and a second door behind which the Mystic Urn and an Inferno Orb can be found. (sector 331)

Firemace
In case the Firemace has appeared at the level startup, you will find it from one of six different positions. In order of appearance, they are located:
 * Room at the top of the spiral stairs near the starting room.
 * Ambush chamber behind the yellow key.
 * Balcony above the blue door hall (north side).
 * Balcony above the blue door hall (south side).
 * On the wooden throne in the green door area.
 * Lowering barrier in the outdoor area near the end.

In single player, this is the last map in the episode where a firemace might be collected.

Player spawns
This level contains five spawn points:
 * 1) facing south. (thing 111)
 * 2) facing west. (thing 112)
 * 3) facing east. (thing 113)
 * 4) facing north. (thing 114)
 * 5) facing east. (thing 115)

Things
This level contains the following numbers of things per skill level: