another idea for living dead could be to keep most of it the same just when you get put to one percent give the player a duration in which they cannot take damage but cannot be healed by another player either.

then for the duration of walking dead give the player a potent bloodbath effect as a means of removing the effect themselves as this would allow the tank to deal with the death if not fully healed without the healer just going into a panic and just removing the effect the moment you hit 1 percent.