Nix

A counterspell built to punish exactly one thing: the spell that arrives without a mana payment. Force of Will pitched to its alternative cost, anything put on the stack by cascade, a suspend card resolving off its last time counter: all of it falls inside the window. A creature hard-cast for its printed mana does not, and neither does a miracle, since paying a miracle cost still spends mana. That makes Nix a hoser dressed as a counterspell, a card whose entire utility is contingent on the opponent choosing to cheat on mana. The design idea is older than the printing itself: efficiency in Magic has always been measured in mana spent, so a spell that asks "what did this cost you?" and answers anything paid-for with nothing is policing the precise axis the format's most explosive plays try to break. The crucial wrinkle is that the cost it checks is literal mana paid, not converted mana value, so the same Force of Will is fair game pitched and untouchable hard-cast for five. It reads like a one-mana hard counter and behaves like an answer with a single matchup in mind, which is the tension that has kept it a curiosity rather than a staple: against a fair deck it is a dead card in hand, and against an unfair one it can be the cleanest possible response to the turn that was supposed to end the game.