I don’t recall reading this in the list of features … if it is there then my bad … but if it isn’t … you would have to create this feature yourself. There are several approaches you could take here and they could involve some form of sphere trigger that prevents damage going through, a flag on a user that you check when applying damage, giving the player 5 times the health for the second, implementing tele-fragging … the list goes on.
Good luck.