Brunia Mauve

When Brunia Mauve enters the battlefield, reveal
the top ten cards of your library. An opponent separates those cards into two piles. Put one pile
into your graveyard and exile the other face-down
under Brunia.
At the beginning of your upkeep, you may pay 3
life. If you do, reveal a card exiled under Brunia
at random. Until end of turn, you may cast that
card without paying its mana cost.