Bend Fate

Exile the top five cards of your library. An
opponent separates those cards into two piles. You
may play lands and cast spells from one of those
piles. If you cast a spell this way, you cast it
without paying its mana cost.

"It wasn't all that difficult, as long as you were with
Abeloth. The hard part was knowing what she was—
as much as that's possible—and convincing
yourself to stay close to her anyway."