Sasha, Purifying Acolyte (276) [Radiant Origins]

Life: 4 Foster (At the beginning of your recollection phase, if this ally hasn't been dealt damage since the end of your previous turn, it becomes fostered.)
On Foster: Banish all cards in all graveyards.
If one or more cards would enter a player's graveyard while Sasha is fostered, banish them instead.