The player who loses life is the player who controlled the creature when it was put into a graveyard. This may not be the player whose graveyard it was put into. That player loses life equal to the creature’s toughness as it last existed on the battlefield.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.