Father Time

When Father Time enters the battlefield, all
players shuffle their their graveyards into their
library. If there are no cards in a player's
graveyard, they must sacrifice a creature with
the highest total power among their active
creatures, then shuffle it into their library.
{t}, {b}{w} If a creature was killed last turn, you
may resurrect it and add it to your hand. if
multiple creatures were killed, select the one
closest to the top of your graveyard.