Being still undecided about the cooldown versus huge Sap cost thing, maybe we could evolve the base idea a bit.
Instead of the caster "jetpacking" backwards a few meters it would make more sense if she were to propel close enemies further away. Essentially being a "push" action. Like Magez hinted at: It would make sense for spellcasters to develop a method to protect them from melee attacks in various different ways because they usually do not wear much armour and may withstand less damage than the average fighter type.
So instead of introducing a push-back of the caster we could introduce a push back of mobs or other players. The benefit of this idea is that it makes more sense in the evolution of things (like Bitty hinted at) and it would allow for more variety (single mob vs "spread", push back distance).
Instead of the caster "jetpacking" backwards a few meters it would make more sense if she were to propel close enemies further away. Essentially being a "push" action. Like Magez hinted at: It would make sense for spellcasters to develop a method to protect them from melee attacks in various different ways because they usually do not wear much armour and may withstand less damage than the average fighter type.
So instead of introducing a push-back of the caster we could introduce a push back of mobs or other players. The benefit of this idea is that it makes more sense in the evolution of things (like Bitty hinted at) and it would allow for more variety (single mob vs "spread", push back distance).