Fireblast

The printed cost is a fiction. Six mana for four damage at instant speed would never see play, and that is the point: the mana value exists only to anchor the card's true line, the alternative cost of sacrificing two Mountains. That clause turns a burn spell into a closer. Committing your land drops as ammunition is only a tradeoff in a deck that has already decided the game ends this turn or not at all. Red aggro spends its mana developing a board; once that board has done its work and the opponent is in single-digit life, the lands themselves become four more damage that costs nothing else. The design discipline is the sacrifice itself, a real and permanent resource cost that prevents the alternative from being free. Each cast strips two Mountains from your battlefield, so firing it usually means conceding the long game in exchange for ending the short one. That tension keeps it a finisher rather than a removal spell: it converts the burn deck's own mana base into reach at the exact moment reach matters. The instant-speed timing is the other half, letting it answer a stabilization play or punish a tapped-out opponent during their own turn. Few cards have so completely divorced their printed cost from their actual play pattern.