Super haste

Super haste is a keyword ability which has only been seen in Unhinged, namely on the card Rocket-Powered Turbo Slug. Super haste allows a creature to "attack the turn before you play it", that is, put it onto the battlefield tapped and attacking during the player's declare attackers step. Then, during that player's next turn, they must pay that creature's mana cost or lose the game at the end of the turn.

According to Mark Rosewater, the Pacts in Future Sight (e.g. Pact of Negation), which are similarly "buy now, pay later or lose the game", were inspired by super haste, representing the notion of "borrowing from the future".