Bloody, you just reminded me of a character I had who wished for immortaily back in the days of Effriti wishes. He lived forever, but there was no guarantee that it was good for him. If he hit -11HP, he was still alive, just suffering in a way no one would ever want to. So this one time the party is hauling his dessicated body through the dungeon after they're out of healing. He'd been hit by a dehydrate spell a few rooms back and was alive but incapacitated at negative twenty something hit points. And before the party gets more healing, they stumble into the throne room of the Big Bad Sorcerer running the dungeon. Big Bad pops a prismatic sphere, and is about to throw his first blast spell of the fight once the round comes around to him again.
So: 2nd edition D&D, Prismatic Sphere. He's pretty much immune to most range/magic attacks, and the only way to take it down or make a melee attack is to run into each layer of the sphere and not get killed as that layer does whatever it's going to do to you, right?
So the party strongman thinks on his feet. He hauls back and chucks my Can't Die No Matter How Much He Suffers character at the sphere. Layer 1: failed save. Maximum damage. Layer 2, made save, half damage. Layer 3, and I'm already getting around -100 hit points, failed. We luck out when I hit the plane shift layer: save made. The thrice blasted raisin of a PC sails on. Not so lucky with the save or insanity layer. At the end of it all my character was insane, poisoned, and more than 100 HP in the hole.
Yeah, those were the days.