[PK]

Your mage player cannot do that. Energy for spells is not spent "per second" -- it's all spent at the end of the ritual, at once. There are a few exceptions -- primarily missile spells -- but they're just that, exceptions. The rule is that you have to pony it all up at once.

Now, said mage could certainly concentrate for 2 seconds, then spend 10 ER and 10 FP. He'd get the ER back the next second, but he'd be tired as all heck . . .