Skirk Prospector

Goblins were a tribe long before they were an engine, and this one-mana hinge turned the difference into a combo. The trick is the recursion of color: every Goblin you sacrifice pays you back the red mana to deploy or activate the next one, so a board of bodies becomes a fuel reserve rather than just a clock. That conversion (creatures into mana, mana into more creatures) lets Goblins chain explosive turns instead of merely attacking, which is the whole reason the deck has wanted a dedicated sacrifice outlet at the bottom of its curve. The body is incidental; the cost to fire the ability is itself a Goblin, so the Prospector can eat itself when the board is otherwise empty, closing the loop on its own. Pair it with anything that makes Goblins for free or cares about death triggers, and the ability stops being ramp and becomes a sacrifice engine that happens to produce mana. Decades of Goblin support have been printed around the assumption that some cheap sac-for-red effect anchors the floor of the manabase; this is the original, the converter that turns a wide tribal board into the velocity that makes the archetype dangerous rather than fair.