billking said:
I honestly don't like the idea of trading divine for arcane spells. It seems like a great way to be cheesy.... I can just imagine a high-level evil cleric with this feat keeping a wizard or two in the dungeon just so he can cast fireball as a third-level spell, while keeping his superior attack bonus, hit die, and saves.
That would be the reson I'll allow it!
I can imagine adventures based on it:
Rescue (or kill) that sorcerer in the dungeon so that the evil cleric necromancer can't use her tsunami spell.
A mage badly need an asian spell to complete his magic item creation, and need a carrier to get the spell for him.
an assasin give an ultimatum to get a signature spell to kill someone, and the sorcerer (who will be accused if he trade the spell) ask the PC to find her child that the assassin kidnapped in order to get the spell.
But I think that to be balanced, you'll need to restrict it to spell slot (i.e. a 3rd level spell can only be exchanged against a 3rd level spell) otherwise, the player who have the feat and a bit of money might buy the price for the casting of a spell and get a meteor swarm to fight the Large white dragon. This is the major flaw and might break the CR and EL rules.
Other things you'll need to rule are:
how the DC (and other variable statistics) is calculated? is the DC fixed by the person casting the spell, by the one trading it, or a fixed DC with minimal "normal" stats(i.e. 1st level DC 11 caster level 1 int 11, 2nd DC 13 int12 caster level 3, etc...)?
Sorcerer do not memorize spell, if they do not expand the slot, can they keep it as long as they do not use it?
If so wouldn't it be more fair to let other spellcaster keep it as well if they want(as you don't have to rememorize every spell each day).
If not, then a fixed duration might remove the asian scenario
Does the sorcerer need to exchange a specific spell or is it a free slot from her know spell (metamagic included or excluded?)?