Arceus, Alpha God

As long as you have 1 or fewer cards in hand, Arceus, Alpha God has vigilance and haste.
Whenever Arceus, Alpha God attacks, look at the top 6 card of your library. You may exile a legendary creature card from among them. Put the rest on the bottom of your library in a random order. Until end of turn, you may cast the exiled card without paying its mana cost.