E1M8: Phobos Anomaly (Doom)

E1M8: Phobos Anomaly is the eighth and final map of Knee-Deep in the Dead in Doom. It features a boss battle with two Barons of Hell.

Walkthrough
Walk forward and click the switch. A room full of demons will be revealed. You can kill these from your vantage point, using the exploding barrels to help. However, consider letting these and other monsters in the level live to help battle the Baron bosses through monster infighting.

Cross the room and ride the rising floor up to get a computer map, box of ammo and health.

Jump down and go down the steps going north. Secret #1 is on your right, but at skill levels 3 and above, you may want to defer picking it up until you deal with the two demons in the side rooms ahead. This will ensure maximum health for the boss battle.

Ahead there are rooms on both sides of the hallway. In the right (east) room is a chaingun with ammo that is needed for the boss battle (unless of course you're still carrying weapons from earlier levels). In the west room is a shotgun that is not really needed.

Continue north and click the switch to lower the lift. Ride up, and as you move forward, two doors will open allowing the Barons to emerge from their tomb-like structures.

Your objective now is to kill both Barons. These monsters (at 1000 hit points each) are much tougher than any others encountered in Episode 1. However, they can usually be killed with five direct hits from a rocket launcher, if you have one. Otherwise, it will take an average of 100 bullets from the chaingun to kill each one, varying widely from about 75 to 125, maybe more since some of your shots will likely miss.

The Barons counterattack by hurling green plasma balls at you (and scratching if you get too close). There is an invisibility at the western point of the star-shaped battlefield that will help you avoid the plasma. The other four star points contain ammo and health that you may need.

When you have killed both Barons, the walls of the battlefield will lower. Jump down and head toward the structure to the north (which does not show on the automap). Click the switch on the left side to raise the stairway. Go up the stairs and step onto the marble-textured teleporter pad.

You will arrive in a pitch-dark room with many monsters and, more importantly, a health-draining floor which you cannot escape. When you die, the level (and the episode) end.

Secrets

 * 1) At the bottom of the steps leading from the entrance area, there is a secret door on the east wall revealing a soul sphere.
 * 2) (Not needed for 100% secrets): When the player encounters the barons of hell, they emerge from pillars.  Inside the east pillar there is a secret door on the east wall; this reveals a switch. The switch causes the elevator to lower back down, allowing the player to return to earlier sections of the level (and possibly restock on ammo).

Routes and tricks

 * The computer map and shotgun are not needed, so the areas containing these may be bypassed.
 * If the player is positioned at one of the five points of the star-shaped boss battlefield, demons and spectres cannot get close enough to cause damage.
 * It is possible, but difficult, to jump directly from the boss battlefield to the top of the teleporter structure, thus avoiding a delay waiting for the stairs to rise. The player must jump just as the lowering wall meets the level of the battlefield, in effect extending it out further. Some of the speedrun demos below demonstrate this maneuver.

Records
The Compet-N records for the map are:

Technical information
Having the walls lower when the last boss has been killed is a special effect built in to the Doom engine. The walls to be lowered are given the special sector tag of 666. However, this effect works only for certain levels and monsters.

Because the level uses this effect, and there is no other way around the walls, it is impossible to complete the level in "no monster" mode (except by cheating).

The damaging floor in the last room is a special sector type (11), more specialized than the usual damaging floors. It turns off "god mode" if it is on, and ends the level when health is depleted. This sector type can be used in PWADs, but rarely is.