Will of the Forsaken (This ally cant leave play unless it has fatal damage or 0 health.) When Charkov enters play, each player puts an ally from his party into its owner's hand.
FAQ
Ally—Undead Priest, 3 [Shadow] / 4 Health Will of the Forsaken (This ally can’t leave play unless it has fatal damage or 0 [Health].)
When this ally enters play, each player puts an ally he controls into its owner’s hand.