Gundam wing. Still my fav Gundam series.

I would say remove the extra damage for them using a spell after hit then maybe switch to "if they use a spell of equal or lower level then this spell" and make it so the ability can be upcast. That makes it so if you use it as a level one it only cancels level one and lower, not all spells. Could also make it more like a preemptive counter spell by removing the save if you do that but that may also be to strong.