Based on this: https://en.touhouwiki.net/wiki/Hourai_Elixir
Once consumed, the player can never die, and is immune to negative potion effects. Upon "dying," the player loses their immunity for a while and gets increasingly worse debuffs the more they die sequentially. "Dying" is in quotes because your player will never actually perish, but you will revive on the spot with the aforementioned debuffs.
Of course, such a powerful item is unobtainable in survival.
