Zivo 'Vonam, The Devious

When Zivo 'Vonam, The Devious enters the battlefield, each player puts the top four cards of their library into their graveyard. Then you
put a creature card from a graveyard onto the battlefield under your control.
{2}{u}, {t}: Each player discards his or her hand, then draws cards equal to the greatest number of cards a player discarded this way.