Re: Counters to problems? (Such as AoE spam and magic overuse)
I beg to differ.
Tuala Morn doesn't call it that, but its Draichta magic system is essentially a quick-and-dirty Multipower. The Perk you buy is essentially a control cost, and then you pay 1 point per spell, which is about what most spells would run as a slot. If you costed out the actual spells of any given character as a Multipower, I'd be willing to bet that the point cost wouldn't be far off from the system as written.
The Arcanoi Segalos of the Atlantean Age are Multipowers.
In the Valdorian Age, having a Multipower is one of the things that sets a true sorcerer apart from a hedge mage.
I don't have the Turakian Age, so I can't speak for that, but that's at least three of the four major fantasy settings produced by Hero Games...