With Acid, i wasn't thinking about acid tube, but some killable pattern that kill you when you spawn, unless the last room is occupied.
But forget it, it's a litle bit stupid and it kills ppl for nothing...
I was thinking about it and there should be an other way to the last room that open when the first team reach it. This new path open 4 minute after the first team reach the last room, and every floor are connected to this path (Can be a teleporter or a looong way you can take without beeing able to go in it backward) So the last team can take it to go in Last Room and fight to death!!! (First team got advantage in this, and there is not a great Time to wait for the other team that cant do the maze fast enough)
Of course, the Fight Room should be bigger!!
Think about it!