Dualcaster Mage

Copy a spell at instant speed, with a 2/2 body attached. That is the whole engine, and it is far stranger than the rate suggests. Flash is what turns a fragile body into a combat trick, a counterspell tax, and a combo piece at once: hold it up, wait for an opponent to commit removal or a draw spell to the stack, and flash it in to fork their own resource back at them. The copy is a separate object that resolves independently, but the trigger still targets the original spell, so an opponent who counters or bounces that spell in response leaves the trigger with no legal target and the copy never happens. The reputation comes from the loop it discovered: pair it with a spell that makes a token copy of a creature (Twinflame, Heat Shimmer, Dual Strike), and the Mage's trigger copies that spell to make a second Mage; each new Mage points its trigger at the copy spell again, and the two feed each other into arbitrarily many Mages. Because those spells grant haste, the swarm simply attacks for lethal with no additional outlet required. What makes the card memorable is how thin the line runs between its two lives: the same trigger serving casual two-for-ones is a tournament-grade combo half, and which side you land on comes down entirely to what you point it at.