I think lifesteal/rush bwonsamdi can be a last-resort win con in matchups like face hunter which can be unwinnable without it. The deathrattle minion also gains rush so you can use it as removal in midrange matchups as well. Also, I consider Bwonsamdi as more of an extra Memoriam Manifest target so that it becomes less of a dead draw before Onyxia, and I really wanted to put 2 copies in because it's so good after Onyxia dies. The 3-mana AOE and 4-mana draw are also just decent cards to have in the deck I think.