True immortality is, as I said, reserved to Kalama and the lord of the Void. Cirno is fine because she's following a piece of lore and is obviously not a combat character, and Deadpool's given limits that don't exist in canon. And as I noted with Deadpool, all upgrades go towards that immortality curse even with those limitations placed on him, and even then he's not immune to death, he just doesn't stay dead when he does die.