(hi i had these ideas, which ideally would always work, even after the Muzzle effect which prevents MaxHP gain in endless/infinite mode)


via a Card, a Potion, and a Relic...

for the relic "HealthStone": Whenever you lose MaxHp, put that many charges/counters onto the relic. Then at the end of each combat and floor you rise, lose a counter, and increase your current HP and Max HP by 1 (so if you had 29/30 it would put you on 30/31hp).

for the card "Prevailing Regains", it would would be something similar, but would read (if you have lost any Max HP this combat, get back half of what you lost rounded up). + If you would lose any Max HP this combat, get back half of whatever you lose, rounded up at end of combat).

and the Potion "Potion of Heartyness" would be similar, to the card (except that it would also regain you 1 Max HP for each attack that actually damages an enemy, but nothing if that attack is fully blocked). :o)