Yeah, I dunno if I'd say he is under "threat." The common problem with super max OP MCs, pretty hard to make it seem like they are under threat at all.
And then!! A bigger calamity came! And then, and then! Space aliens used an orbital ion cannon but he like reflected it and they EXPLODE! And theeeeen!
Why not just start out with a full power attack. If that doesn't work you're dead anyway so why waste power with little attacks limiting an all out final attack. Well not doubt he'll craft a walking stick with insta-kill S+ effect or something.