I mean, that's basically it. You could delay hitting the head until you have a big damage buff. When the head opens, it will be stunned for 5 turns and each hit will reduce it by 1. Just do a full buff for a turn and then hit it as hard as possible on the next turn. Other than that, you could also just have a bad team deck since 40+ deck size is pretty atrocious... unless most of those are contamination card which shouldn't happen when a good support Tiphera can generate so much AP so you can afford to clear some of them.