Charon, Harbinger of Hell

+1: Pay X and 2 life. Target creature with mana value X or lower is now a 1/1 skeleton token under your control.
-2: Pay 2 life. Return target creature from a graveyard to your hand. If that creature is not from your graveyard, pay an extra 4 life.
-X: You gain X life. Creatures with mana value equal to half of X that are currently in a graveyard are now on the battlefield under your control.