the final sign youre right below the ur-ghast is when you get to the floor with one of these in it. this looks like an awesome freebie of gold and diamonds fro doing a good job and getting this far up the tower but no, its a trap. to be honest youre better off taking the free redstone and pistons. the only reason i noticed was i was able to look up from my confusion long enough to read my NEI block description and read "reappearing block". this thing lures in the player with false promises and then destroys the room around them and tries to make it impossible to get to the next floor. if the player doesnt fall it doesnt matter because most of the room is taken out and youll need to build to the staircase and will most likely fall anyways. and if the player gets close enough before it explodes, that should kill them. but as a fail-safe, when the reactor explodes it summon ghast guards. just a final "fuck you" to the player with love from the ur-ghast. there will be about 3 floors of these before you reach the boss. either fly by them or take your free loot. but activating them isnt recommended. mods installed so far are: backpack, battle towerrs, bibliocraft, buildcraft, chococraft, clonecraft/mypeople, damage indicators, dungeon pack, enchanting plus, eternal frost, exrtabioms xl, familiars, galacticraft, galacticraft planets (mars), iron chests, jammy furniture, lucky block, lumberjack, lycanitesmobs, minecraft comes alive, mo chickens, mo cows, nether x, not enoug hitems (for crafting recepies), optifine, ore spiders, rogue like dungeons ruins, the lion king, travelling house, tropicraft, twilight forest, and zans map. (plus all plugins required for each mod).