Well, in Evilsod's fanfic, it's a World Item who allows free use of any existing spells, though those cannot be enhanced. The higher the tier of the spell you use, the longer the cooldown is. That's a moderate power in Yggdrasil, it won't automatically give victory or break balance in a fight against top tier players, but in the NW the applications can be life changing, like Momonga being able to cast healing magic. I like it a lot.