I sneaked up to hear that there was a fight between the NPC's for some reason, and as I got closer the fight ended and there appeared a line of mages and undead heading out of the towers lower pathway towards the exit with a resurected mage in tow.
It seems like the AI deciced for some reason to kill one another and it completed the quest for me. Now that may sound like a "cool" thing, however its the job of the PC to do these things and it rather makes my efforts towards doing it rather pointless if this kind of thing happends more often (ie NPC's in fighting).
Please not I did not cast any magic nor did I use anything other than a bow and I only fired a handfull of shots and nowhere near the actual tower.
