How's this sound?
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While evocation is technically capable of many tasks, many of them require considerably more skill, practice, and luck than most wizards put into it.
So what are these 'other' uses of evocation?
Many skill rolls can be outright replaced by evocations, examples include moving (force jumps, 'tactical' hops through the nevernever, etc), very fine manipulation of objects (lockpicking, eavesdropping, fine craftsmanship, etc), illusions of considerable complexity, etc
In general, the power of the evocation will act as a roll of the appropriate skill.
You can gain access to the 'other uses' of evocation in the following ways:
1
Spend a fate point, to get access to the ability for a single use.
2
spend a point of refresh of a permanent expansion of your evocations to cover one trapping of a skill.
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So, for example, if you want your wizard to force jump occasionally, you can spend a fate point, and then use the evocation power of the spell in place of an athletics roll. If you want your wizard to force jump all the time, you spend a point of refresh to explicitly gain the ability to do that all the time.
People worried about spirit being the 'most equal' element (gaining access to veils, while other elements can't do anything else), can either add one trapping to each of the elements that you can do with them, or can make veils and ability that requires one of these expansions to use.