I was trying to figure out ways to do this one, and as I was spoon hunting, I accidentally resolved this one.
The key component is a legendary pair of pants "Sacrificial Cloth" that gives you +3 Max HP instead of healing from potions. The great news is, this works with cursed potions as well, so instead of the coin flip to hurt or heal, you just get 3 Max HP as well. You can still lose the coin flip, but I had a paltry 8 for my rating and got at least 80% of mine to hit. If you see this early, take it, and just chug-a-lug, it should pop immediately after hitting the 100 max hp mark. I got this off of an early assault, and ended the light battle with over 180 hp.
Of course, since you aren't really healing, make sure to get something that helps, I had the Bloodstone from the Sacrifice well which does wonders.