Sy, you know I am not one to give away immortality cheaply. Am I not having this very argument with ATH about Noir? Remember that guy that wanted to play the wasp queen, and send out her wasplings on missions?
But since it is an issue: These guys coming back are a direct result of Asiin's wish, and are, as Terrance is, not player characters anymore.
They can be killed again and it will be final, as there will be nothing driving their return. Not that that matters for the player. They've already lost their character.
Now, about fairness. The way I had intended this game to be set up was that two characters could be completely imbalanced in relation to one another in a variety of ways. A weak troll is still far stronger than a powerful cat, for instance. and a smart troll is still a fool by most standards. So if someone says "I want to be a robot" well, they get robot powers and problems. If someone says instead, "I want to be a bodyless leaf creature that doesn't believe in magic" they get powers and problems of a completely different nature. Zombies and other undead have some things going for them that other races (or rather, living versions of the same race) don't, and some things pulling against them that others don't. It might not be exactly balanced. But I don't really care about that as much as I am interested in giving real challenges, interesting experiences, and a fun game for each player. I try not to let any character break the game for the others, if possible, but I am not concerned about making all creatures equal and balanced either.
Of course, as varied as the initial set of characters was, some of my careful attention to base race imbalances got lost in the shuffle, but I think that worked out for gameplay purposes well enough.