Stenchskipper

A 6/5 flyer for four mana is a wildly aggressive rate, and the design pays for it with a leash rather than a drawback you feel on cast: keep a Goblin on the battlefield or the elemental walks off at the end step. That conditional is doing the same structural work that an upkeep cost or a sacrifice trigger does elsewhere, but it points outward, tying a black bomb's survival to a creature type black does not natively produce. The tension this resolves is a familiar one for oversized beaters: how do you hand a deck a body this far above curve without it dominating any list that runs the color? Here the answer is a tribal toll. You are not paying mana or life each turn; you are paying a deckbuilding constraint, committing to a Goblin shell deep enough that you will reliably have one alive when the end step checks. The check is generous in one direction (any Goblin satisfies it, not a specific one) and unforgiving in another (lose your last Goblin to a sweeper and the flyer follows it to the graveyard the same turn). It is a creature built for a tribe that rarely flies and rarely hits this hard, smuggled into Goblin decks on the condition that they stay Goblin decks.