Sephiran, Goddess' Right Hand

When Sephiran, Goddess' Right Hand enters the battlefield or attacks, look at the top 3 cards of
your library. Add one to your hand and send the others to the graveyard.
During your upkeep step, if you have ten or
more cards in your graveyard and five or more in
your hand, transform Sephiran, Goddess'
Right Hand.