Though I agree that Orbius probably doesn't make sense as a grapple there are defiantly ways I could see evocation being used to create a grapple like effect such as increasing the gravity around someone massively so they can't move at all, earth burial (open the ground under them then shut it), chains of air or simply holding people with spirit. Evocation both in the Novels and in Your Story can clearly be used to block pretty much any physical action so magical grapples (or at least blocks against multiple actions) are appropriate but given block rules they should be breakable by any roll they block (so any appropriate skill) and following evocation rules a block shouldn't cause stress on the side.