The concept is simple. Especially in non-ranked games, people die and immediately quit the game. It makes the medium and the ret increasingly frustrating to play. I've won more games as ret being turned vamp than as ret.
So the buff is simple, though it could cause complications: When you die as a town member, you are alerted to the presence of a role that interacts with the dead. Something simple, like, "You feel a lingering connection to the living world.", thus not telling you which role it is. If a medium is trying to stay incognito to the dead (dunno why they would) they could, and if it's a ret you have a legitimate reason not to leave the game until you've seen it play out.
If nothing else, we need to do /something/ with these two roles. Ret is extremely powerful, but you have to reveal yourself to everyone before you revive someone when everyone is quitting. It opens you up to all sorts of complications that you wouldn't have to deal with if people quit leaving. And medium is more of a joke than a role most games.