E3M8: Dis (Doom)

E3M8: Dis is the final map of Inferno in Doom. It features a boss battle with the Spider Mastermind. Dis is named after the capital city of Hell that appears in the "Inferno" section of Dante Alighieri's book novel The Divine Comedy. It uses the music track "Facing The Spider".

Walkthrough
To complete this level, the player must kill the Spider Mastermind, which appears here as the Boss for the episode (A). She appears on the bottom right 'clover leaf' of the map with a Baron of Hell (on harder difficulty levels) in the top left leaf and two Cacodemons occupying the other corners of arena. Almost all ammo is on a raised walkway above the main arena containing mostly of rockets and a few cells (B), except for the Plasma rifle, which is in a small room in the center of the map (C). The only way to access the walkway is from a set of steps to the north of the central building, or by walking along the walkway upon entering the level. This lack of ammo provides extra challenge and you are vulnerable to the Spider's hitscan attacks. As there is barely any cover (except for the thin pillars where the Plasma Rifle and Mega Armor is located), to protect yourself from the Spider's bullets, moving quickly is key to survival here. There are no health recoveries here, so make your health count.

An effective strategy for this level is to deliberately cause the other monsters present on the level to attack the Spider Mastermind. The Spider Mastermind will then become preoccupied battling with the other monsters and will ignore the player's fire until the attacking monsters are killed. For example, you can move behind a Cacodemon, and the Spider will try to fire at you, but will fight the Cacodemon instead. Fire at the Spider from behind the Cacodemon, but don't fire at the Cacodemon! Eventually, the Spider will kill the Cacodemon, but the combined forces against the boss will cause it to die faster (see demo below). This method is a good way to distract the Spider in battle so you can collect the ammo that is sitting the outer ledge. As a consequence of the extra ammo and monster respawning of Nightmare skill, this is one of the few levels that is generally easier in Nightmare mode than Ultraviolence.

If you have the BFG9000, this boss fight is extremely easy. The Spider Mastermind will die in one or two direct hits (if you are close enough to it), making the battle a piece of cake. Otherwise, use monster infighting and the Rocket launcher/Plasma rifle to defeat the boss quickly.

Official
There are no official secrets in this level.

Non-official

 * 1) The small room in the middle of the arena contains a Plasma Rifle and a Combat armor (note that the doors won't automatically close once they have been opened).

Bugs
Nineteen rockets (Things 35-53) have no flags set for any of the difficulty classes, so they do not actually appear in the level.

Sector 1 is unclosed, as the front sidedef of linedef 21 and the back sidedef of linedef 57 reference their own sector (sector 2) instead of sector 1.

Records
The Compet-N records for the map are:

Demos

 * [[Media:E3M8 Spider Infighting.lmp | E3M8 being completed by exploiting monster infighting]] (file info)