- The big AOEs were glyphs for adding elemental damage to weapons - basically works the same as the Templar blessed weapons ability. I believe we opted to make the Templar one more unique by just not having the mage ones
It would have been overpowered anyways because it actually changes the damage type to be fully elemental. IMO elemental damage should always stick to mages. I think a self-buff that allows mages to temporarily change their staff element would be cool
I was thinking about another mechanic earlier today but it doesn't look like it would be possible to implement. Basically portals that allow you to move between two points or phase through walls.. I'll have to look how fallback plan is implemented 
One issue is how the maps in MP are mostly small/corridor maps (with no obstacles in the middle, ugh) with a ton of no-go zones (dead ends) that serve pretty much no purpose other than chokepoints, so being able to warp back and forth to use that extra space would be cool (as long as it's done in a tactically meaningful way)
Trying to come up with new mechanics is kinda hard. I want to implement a dodge badly, but don't really want to go the dark souls way of repeating the attack/dodge (roll!) pattern that gets repetitive super fast. It also would be unreliable unless I slow the combat down quite a bit. Another way would be to add some form of CC to the dodge, but not sure how just yet