Lava Dart

One damage, twice, paid for once in mana and once in land. That second cast is what sets this apart from the long line of one-mana pingers: the flashback cost is a Mountain off the battlefield, not a card from hand or mana from your pool, which means the spell costs you tempo on the back end rather than resources up front. The arithmetic is precise. Against the toughness-one creatures it was built to kill (mana dorks, early aggressive threats, the small bodies that prop up tribal decks), it removes two of them across the game for a single card, with the second shot deliverable at instant speed whenever a Mountain is expendable. Burning a land late, when you have enough red sources to spare, is rarely the cost it looks like; the design banks on the fact that the back half of a game has surplus lands the front half does not. That makes it a card-advantage engine wearing a burn spell's clothing, which has kept it in dedicated red decks that can stomach the land sacrifice rather than splash decks that cannot. The damage number is deliberately small: one point is enough to clear the X/1s that define so much of the early board, and small enough that pushing it to the face is almost never the play.