The Soul Stone

{6}, {t}: Return target creature from your graveyard
to the battlefield. If The Soul Stone leaves play,
put creatures returned to play by The Soul Stone
back into the graveyard.
"The Soul Stone holds a special place among the
Infinity Stones. You might say, it is a certain wisdom.
In order to take the stone, you must lose that which
you love. A soul for a soul." - Red Skull