Gremora, Penvari Duchess

When Gremora, Penvari Duchess enters the battlefield create X 2/2 Zombie creature tokens,
where X is the number of creatures in all players graveyards.
{2}, put a creature card from exile that an
opponent owns back to that player's graveyard:
Draw a card, if this is the third time you've
activated this effect this turn, exile Gremora,
Penvari Duchess and return her to the battlefield
at the beginning of the next end step.