Okay, so things happened last night. When you are reading this post, it will help you if you also think of it as a "what not to do" sort of thing.
The party fought two combats. On their third combat, they fought a
gibbering mouther and almost lost Ullar's gnome gunslinger, Riggs, when it was engulfed. Agape's druid/monk, Butterscotch, used liberating command twice, and Riggs was spit out. Eventually, they defeated it. All in all, this combat went fine.
After this, they descended some slippery stairs 40ft (nobody slipped and broke their next though), bringing them into a large, dark chamber with a curtain on the far end, and a box in the middle of the room. Three of them clustered around the box, and they opened it. A Stone of Alarm was set off (it made a really loud screech), Riggs, the pregen character Valeros, and LightWolf's gunslinger Inmissam all got hit with a Lightning Arc trap for minor damage. These 3 were also covered by the spider swarm that was in the box.
As apparently only Butterscotch had a way to deal with a swarm, and it was acid flasks. However, she could not hit the swarm's touch AC without rolling well. Inmissam dumped 3 doses of black powder on the ground, asking for each does to deal misfire damage (1d8) when it exploded. This sounded fine with me. Inmissam then had Butterscotch firebolt the powder. She did, and crit. 6d8 damage, rolled 19 damage. The swarm died. Inmissam was hurt pretty badly.
They healed up and, forgot all about the alarm they set off (even though I said it had stopped screeching by now), and the explosion they had just made. Their plan was to all jump through the curtain at the same time. The room on the other side of the curtain, as they found out, was well-lit. They did this, and jumped right into the middle of 5 fast zombies who had readied actions to beat the shit out of them. Two of the fast zombies confirmed crits, and Butterscotch, Inmissam and Valeros got beat up. The Rogue 1/Sorcerer 3 in the room also threw a magic missile at Valeros. The sorcerer was joined to an archway by large umbilical cords, and could not move more than 20 feet from the archway; this would be relevant.
After initiative was rolled, the zombies and the sorcerer rolled pretty well. 3 zombies and the sorcerer went before most of the party. Butterscotch was downed. On their rounds, the party dropped a zombie. As the enemies went, they dropped Valeros, and beat up Riggs. The party dropped another zombie. Riggs and Inmissam got attacked; I don't recall how much damage they got dealt; I know Riggs had 1 HP.
It was at this point that they would have tpk'd if I had not been very very nice and given them detailed step-by-step instructions to try and save their skins. It worked, and I probably won't be giving such detailed advice in the future. Inmissam pulled Butterscotch back into the dark room, and then the zombies knocked him unconscious. Riggs ran past the zombies and up the stairs, with the zombies following him. Two of the zombies slipped on the stairs, fell, and died. The other one was killed by an NPC once Riggs reached the ground floor.
As the sorcerer could not move very far, and could not see into the dark room, Inmissam and Butterscotch were safe. They healed, and beat the boss, and won in the end. The fight with the boss does not need recounting, even though it was pretty cool. The point here is to show that bad tactics are the best way to get yourself killed.