Shadow of Mortality

If your life total is less than your starting life total, this spell costs {X} less to cast, where X is the difference.

Emrakul, the Promised End

This spell costs {1} less to cast for each card type among cards in your graveyard.
When you cast this spell, you gain control of target opponent during that player's next turn. After that turn, that player takes an extra turn.
Flying, trample, protection from instants

Riddle of Lightning

Choose any target. Scry 3, then reveal the top card of your library. Riddle of Lightning deals damage equal to that card's mana value to that permanent or player.

Blast of Genius

Choose any target. Draw three cards, then discard a card. Blast of Genius deals damage equal to the discarded card's mana value to that permanent or player.