A block is a block is a block.
If outside of combat, what is the effect? Is it a maneuver? A social attack (for something like social combat)? Why are you doing it?
Like was stated, start with the effect, work back from there. Balance, power, etc. relys on the mechanical benefits of the action. Don't over cost something just because it seems like it would be hard to do from our (Harry's) perspective. Thematically, it would use Spirit for evocation, and I'd say Illusion (which isn't in the books but would be something like Veil magic) for Thaumaturgy.
+1.
What do you want to do. Make it harder to hit you? That's a block. Do you want the ability to either make it harder to hit you, OR make it hurt more? That could be a block (remember, you can sacrifice a block to turn it into an attack spell), or just an aspect of
illusory clones everywhere. Tag and invoke as needed.
-EF
