E Commit: Before you attempt to block an attack, you may use any card with a block in your staging area as though it were in your hand.
So my question is: isn't the timing for this one off? Should his ability be an R? From the way it sounds, it has a similar (though not EXACTLY the same) trigger window as Holding Ground, which is also an R. It doesn't state "this" attack, which implies the ability is a floater, possibly letting you use it for the rest of the turn. Or does it work that way (which would be awesome)?