Since you don't need it to last long, it wouldn't be too difficult. Being thaumaturgy, it also has the advantage of not (necessarily) causing stress.
That said, it would be nice to have a similar capability with evocation. What do you think Reflection should cost? A two shift add on to a block? Two shifts might be enough if the block still has to beat the attack's power (as a ward does), but not sure. On the other hand, two shifts per spell reflected seems a bit much.