Font of Ire

Six total mana to deal five damage, none of it ever touching the board, is a rate that only makes sense if the card's whole job is finishing the game from a position where the opponent's creatures have already stopped mattering. It splits its cost across two points in time: it lands for two mana as an enchantment that costs nothing to maintain, then waits until you can spare four more mana and the sacrifice to convert into a single hit to a player or planeswalker. That split is the design lever. A one-shot burn spell demands its full cost up front; this lets an aggressive red deck deploy it early as a threat-in-waiting and cash it later, once the board has stalled and the only resources left to attack are life totals and loyalty. It cannot point at a creature, which is the restriction that buys a five-damage source this cheap to deploy: it is reach, not removal. Its closest kin are the slow-burn permanents that store a decisive release rather than trade with the battlefield, and like those, its value scales inversely with how interactive the game stays. Against a deck that races or builds a wall it is a clock nothing on the board can answer; on an open board where blockers and bodies still trade, it is dead weight where a straight burn spell would have served.