Lavalanche

A board-sweeper with a name attached, and that's the design knot the card ties itself into. Most mass-removal scales evenly across the table; this one picks a single victim and then punishes every creature standing under that victim's banner. The X hits the chosen player or planeswalker directly and rains down on their whole board at the same rate, which folds a wrath and a finishing burn spell into one targeted instruction. The Jund commitment is what pays for the breadth: three disciplines combine into a single line that no two-color pair could write, with red supplying the scalable burn, black sanctioning the indiscriminate damage, and green underwriting the X you need to make it lethal. The structural cost is that it only ever hits one target's side of the board, so the symmetry that defines most sweepers is gone entirely; you spend mana to clean one opponent's side while leaving your own untouched. That one-sidedness is the only reason to run a sorcery with this much color requirement, and it explains why the card reads as overkill against any single threat and devastating against a developed board. The wrinkle worth noting is that the player-and-creatures clause lands at once, so a single resolution can end a game outright when X climbs high enough to outrun both a life total and a battlefield in the same breath.