Overly-Great Thing

You can have this magical orb that grants your every wish, but it comes at a price: any wish you make will be granted, but it'll have an odd quirk thrown in.

The thing that has a power that makes it overpowered to our heroes but might have a trait that counters this power, something like what the slidetext said (having the usage of this power come at a price) or never being able to be used because of how the Overly-Great Thing is always moved just as the heroes use it.