I, personally, would love to see a first strike spell.
The concept being that using the spell would change the turn order of battle. This means if the opponents are currently casting their spells first, and you were to cast first strike, then the next round you would cast first, and your opponents second. If you were already casting first then first strike would be useless (unless perhaps your opponents also casted it, which would cancel it out?)
I do not believe this would be overpowering, as really it would not even skip an entire oponent turn like the stun all spells, and it could not be spammed (which is why every stun also gives 4 stun shields). It would certainly provide a great strategic advantage, however, which would be usefull for both PvP and PvE.
Ive not strong opinions on cost or school, I would just love to see the spell period.
Please post your support if you also like this concept!