Anyone who has played a mage knows, and probably hates, when there is
a crucial spell that has one or two hours on it, and that it might
drop before a fight is over. In the case of shifters, stone skin is
a big one. I know mages get cancellation, and what have you...BUT,
why not allow more spells the "renewing" capacity of, say, something
like "water breathing"? This would eliminate something of an annoyance,
I believe, without tipping the fragile "balance".

Bizarro I'm helping!