First Glitch in the first battle when you kill off the Death pig first then die and come back in it does not count. So you haft yo make sure you kill the Death pig last . So for Example:You haft to kill off the minotaur first then if you die it is ok and you will be able to start using swords then when you get back into the game the you haft to kill off the Death pig and then kill off the two balance pigs without dieing and then it will count as you completed the Quest. Helping hint If you want to put shields on the Death pig You need to put Myth Di spells on him. But for every shield you need at-least one Di spell. Second Glitch The last Battle Plain and simple need to kill off the first guy and not die. Because if you do and come back into the game there is a glitch and the helpers are not in there is nobody so you be forced to redo the whole tower all over again. So if you kill off the first one make sure that you are strong enough to kill the rest off.
There's no glitch with the bosses. If you die after killing ANY main boss in the game, and flee and come back the battle is reset. Minions killed before dying will not return in some battles, but that's not a guarantee.