New strategy for the tactical level in TX: Bring a stack of landmines, as many as you can. Drop them right as you enter the level and zap them with a wand of teleportation. Make sure that none of them ended near you, then pray to Silva or read a scroll of earthquake. Watch the level burn.
This gets rid of quite a few enemies (hopefully the spellcasters, too) and opens new tunnels in the walls that would otherwise force you to go around the long way. Unfortunately I still died in the last game as the Xinroch's grave keeper kept destroying my torso.