Zada, Hedron Grinder

The whole engine hangs on one self-referential trick: a single-target spell aimed at this Goblin gets fanned out across your whole board. The wording is deliberately restrictive in a way that makes the payoff feel illicit. The spell has to target only this creature, which sounds like a limitation until you notice that the copies don't inherit that restriction; each one is redirected to a different creature you control. So a one-mana cantrip becomes a cantrip for every body you have, a pump spell becomes an army-wide buff, an Expedite or a Distortion Strike becomes a board-spanning effect for the price of one card. The design is a study in token-deck multiplication that doesn't need a token spell at all: any wide board plus any cheap targeted instant or sorcery is the combo. Its own fragility supplies the counterweight. The ability does nothing while the Goblin is off the battlefield, the trigger asks you to commit the creature first, and the spell must legally target only this one creature, which rules out anything wanting multiple targets up front. Few build-arounds reward their particular deck shape (go-wide, low-curve, cantrip-heavy) this precisely while remaining inert everywhere else. The copy effect is the whole draw, and the narrowness of the targeting clause is exactly what gives those copies their leverage.