Thought this would be fitting. Instead of a Ressurection spell (or maybe 'along with') White/Black mages can cast a Rebirth Obeslisk on living allies. This would create a white cross (or black stone, whatever sprites you have for an evil version) where that ally is standing. When he dies, he'll respawn at that location (still in the 'dead' state for a number of seconds) The stones could also be attacked and only last maybe 5-10 minutes so put them in a good spot.

The spell would be fairly high tier and cost some material like Obsidian ore for black mages and Platinum ore for Good mages.

 

I guess its just more 'interesting' than Resurrection, its more like insurance because your res guys could die too.