Assassin's Blade

Removal spell built as a combat trap, a piece of design that belongs to the Portal experiment more than to Magic proper. Portal was the new-player gateway product that stripped instants out entirely, and the workaround was a class of spells locked to specific windows so the rules engine never had to teach the stack. This one fires only once an opponent has actually committed to a swing against you: the timing clause is the whole design, turning what would otherwise be a generic two-mana kill spell into a punishment that exists only when you are the defender. The constraint is doing real balancing work. You cannot proactively clear a blocker, cannot snipe a creature on your own turn, cannot answer something sitting back on defense; the card is mute until an attack commits, and then it picks off one nonblack member of the assault. The nonblack rider is the other quiet tax, a flavor-and-balance hedge that keeps black from cleanly answering its own color. What you get for accepting both restrictions is instant-speed removal in a set that had no instants, a removal spell that reads as a sorcery in its limitations but resolves in the middle of combat where sorceries cannot reach. The whole thing is a record of how Wizards once tried to fold reactive play into a beginner's vocabulary without ever saying the word "instant."