Flowstone Wyvern

The Flowstone mechanic was Tempest's red-and-black motif: a creature that converts mana into raw power at the cost of its own toughness, and this evasive drake is the cleanest single-card statement of that idea. The repeatable +2/-2 is a pump effect that bills you on both ends. Each activation widens the swing the flier already represents, but every point of extra damage is borrowed against the body's own survival, so the bonus cannot be stacked indefinitely without subtracting the creature out from under itself. That self-inflicted toughness loss is what keeps the effect from spiraling into a free firebreather. It also gives combat a knife's edge the controller has to read: pump too far in a profitable swing and a chump blocker or a one-damage burn spell suddenly trades up, because the Wyvern has spent its own toughness to deal the extra damage. The reward is that mana you would otherwise leave unused becomes a scalable clock; the cost is that the same lever which makes it lethal also makes it brittle, and the pilot pays for it on every activation. Power and fragility springing from one button is what marks this as a Flowstone card rather than a generic pumper, where the upside arrives without strings. Here the upside is always mortgaged against the body holding it.