I used up my Radiance on units. It's not much but I figured, hey, with HOF around the corner, it certainly can't hurt. However, when we're past HOF, I'd save for the mastery point. I value that point extremely highly. Between it and the one you get from the Necropolis and the ones that are coming in future levels, it will make running Recoils much easier. You won't be able to completely max out the Recoil tree, Mystic Dispersion and Deep Wounds all at the same time, but it should still give you more wiggle room. I can't wait!