Strategy:Halls of Carnage
From DoomRL Wiki
0.9.9.7
Hurt Me Plenty / Ultra-Violence
Keep a homing phase device in case this level appears. If it does, grab the mods near the start, kill all the lost souls, and then immediately use the homing phase device to teleport straight to the stairs and the BFG 9000. Once secure, wait by the stairs while the other monsters die in the lava. The doors are locked and can only be broken open with attacks.
If you don't mind not getting 100% kills, you can leave right away. Otherwise, be sure you killed the lost souls, as they will not die in the lava. If you missed any, you'll have to have at least two envirosuit packs to go back and get them if you don't have some form of lava-proof boots, and since the lava destroys everything but the stairs, they'll scatter about all over the map.
Note that this does not necessarily work on HNTR, ITYTD, or N!, as on those difficulty levels there are cacodemons that are also immune to lava.
