Back to the Future

You may cast target instant or sorcery card from
an opponent's graveyard without paying its mana
cost, but with the reverse effect. (e.g. Spells that
take life give life instead, spells that have you draw
cards put cards from a player's hand to the top of the library, spells that have you discard cards puts cards
from a graveyard into one's hand, etc.)
Kicker {u} (You may pay an additional {u} as you
cast this spell.) When Back to the Future was
played, if it was kicked, you