Transcendent Height, Kefla

As long as you have one or fewer cards in hand,
Kefla has Flying and Vigilance.
Whenever Kefla attacks, look at the top six cards 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.