I finally finished the Costlemark Tower secret dungeon. What a shitshow it was. For those of you wanting to do it: ribbons totally negate the instakill attack of the Couerls on the deeper floors, and a ribbon + two mighty guards + shield of the just trivializes most of the floors including the bosses. The four giants are a bitch no matter what you do. I chose to use quintcast blizzaga on them, coupled with healcast blizzard. I ran around the room until my casting cooldown was up.