14 Jul 2017
You (not your opponent) choose which pile to put into your hand and which to put into your graveyard.
14 Jul 2017
In multiplayer games, you choose an opponent to separate the cards when the ability resolves. This doesn't target that opponent. Because the cards are revealed, all players may see the cards and offer opinions.
14 Jul 2017
To determine the total cost of a Sphinx spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions. The mana value of the creature remains unchanged, no matter what the total cost to cast it was.
14 Jul 2017
A pile can have no cards in it. In this case, you'll choose whether to put all the revealed cards into your hand or into your graveyard.
14 Jul 2017
Unesh's cost-reduction ability doesn't reduce the cost to cast itself.