Just like in Skyrim. It recharges over few seconds. The sound is not important, it would be like spell which recharges after few seconds.
That way combat will be more dynamic.
Btw, is there any spell mod which adds dual casting like in Skyrim and dual sword fightning?
And final is there spell mod which can makes that you can make lightning spell more durable -> I mean with holding "C" button lightning doesn't stop.
Thx