Vial of Dragonfire

The whole point of pricing this effect onto an artifact is that the damage stops being a color: any deck, regardless of what mana it runs, can hold two points of removal in reserve. The cost is paid in tempo rather than in cards. You commit two mana to deploy it, then two more and a tap and the artifact itself to fire it, so the four total mana and the single use buy nothing but the timing flexibility of a colorless answer that can sit on the battlefield until the right creature shows up. That delay is also the friction: a removal spell that asks for four mana spread across two turns and a permanent slot pays a steep premium over what a single red card does for the same two damage. What comes back is reach into a board state that an aggressive or controlling deck of any color might otherwise have no clean way to interact with, plus the small upside that the artifact can be cracked the instant a threat lands rather than waiting for a main phase. It belongs to the long line of colorless removal-on-a-rock designs that trade efficiency for universal access, an answer that exists so a deck without a removal color is not simply helpless against a two-toughness creature.