Thats a tricky one. In a campaign I was playing a person used the
sorcery spell Drain(pow) (I think, I don't have my rulebook beside me) to
kill a dragon. I would be tempted to leave it as is. After all it
is essentially one use (per adventure) and lets face it you have an
unlimited amount of creatures to throw at them. As a consolation I know
just how you feel, once when I was GMing a campaign one of the players
casually walked up and criticaled my main creature through the head and
consequently then got into a 15 round combat with some lesser (but lucky)
underling. The reasoning I would use to basically not tamper with this
spell is: That you will probably only see it once per adventure, it does
give the players an essential 'get out of jail free card' for really
tough situations, the guy probably gets his jollies using the spell and
you do essentially have unlimited NPC's.
James.