spoilers!!
Staff of magi is in the twisted rune place. Go to bridge district and find the room with the liche guarding kangaxx's head (or arms and legs, i forget which). Its near the bottom left of the map. Round the corner from that door (next to the water) is another door which leads to the Twisted Rune - i'll let you find out the rest
Cloak of mirroring i think you get just b4 the underdark