Without following all the details of the discussion in this thread:
I tend to use Staff of Magus a lot with my witch. It is true that it does not make too much damage but it is great if you want to finish off the enemies who are already very low on health and do not want to waste precious melee attacks of your warriors. Besides, Staff of Magus is really great if you use it on mobs who are immune to opposite elements: so, a staff of magus cast with water staff does something like 80-90 damage to fire elementals/burning archers etc. It is all about keeping staffs for each element and than selecting appropriate staff before going to combat.
