How to resolve this situation?
 

Energy Reserve: 10
Regeneration (Extreme: 10/second) (Energy Reserve Only)

Time to Cast Spell: 2 Seconds.
Energy Cost: 20

Please forgive the arbitrary numbers, I'm trying to narrow it down as far as reasonable to define the situation. I have a mage with regen reserve, who wants to cast spells with long casting times and also cost more energy than he has available on a second-by-second basis.

Can he cast the above spell, as he can spend 10 energy per second (20 total at the end of the 2 seconds) for the duration of the spell's time to cast?

Does the answer change (and how?) if he uses ceremonial magic instead?

(I have an opinion of how this works, as the GM running the game for the player in question, but I'd like others opinions and ideas to make sure I'm interpreting it correctly.) :)

Re: How to resolve this situation?
 

He needs to have all 20 EP available at the last second of casting, ceremonial magic or no. That said, unless he has limitations on his ER, he can combine them with his FP to get to 20 (unless you've decided that the setting prohibits that, of course).

Re: How to resolve this situation?
 

This issue comes up frequently with the Draw Power spell. No, you have to spend all of the spell's energy at the time of casting, not during the ritual.

"At the end of the last second of concentration, make a success roll for the spell ... On a success, mark off the spell’s energy cost against your FP ..." (p. B235)

Re: How to resolve this situation?
 

For the cost, bump the regen rate down a notch and throw the points into expanding the reserve. THough it is impresive to be able to throw a 10 fp spell every second indefinately it is not as useful as being able to pull out the bigger guns when needed (and still have an amazing recovery rate).

Re: How to resolve this situation?
 

Ah. Something I reference when discussing this with the group. Thank you both.

Heh. The numbers were selected to simplify the question, not to represent the characters' actual capabilities. Thank you for the suggestion though. :)

...

Now to figure out how to make the energy accumulate while casting (even if only ceremonially or something) so that he doesn't need to buy a 10k ER.

Re: How to resolve this situation?
 

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 . . .

Re: How to resolve this situation?
 

Then what would be a good price for the ability to do so? (Outside of buying that 10k ER, of course.) And how would I build that ability?

Re: How to resolve this situation?
 

You'd need to buy enough ER to cover the largest spell you wish to be able to cast. If you plan on casting 30-energy spells on a regular basis, you'll need at least ER 30. You certainly shouldn't need ER in the 10,000 range unless you're planning on casting some very scary spells!

Re: How to resolve this situation?
 

There's two easy things you can do there, first you can simply state that in your setting mages put energy into their spells during the casting process at a rate of (total cost)/(casting time), similar to how missile spells are done.

That's a perfectly reasonable and sensical setting requirement, not only would it answer your issue, but it also more closely resembles most fictional representations of casting where mages are accruing energy and building spells during the entire casting process.

Barring that, the next easiest thing to do is introducing a Hold Spell variant, which allows the mage to continue to put energy into a spell until it reaches the threshold energy to be cast.