Torbran, Thane of Red Fell

The plus-2 is flat, but it applies per instance of red damage rather than per spell, and that split governs the entire payout. Add two to a single burn spell and you have a modest bump; add two to every trigger a red damage engine produces and the output curves away from the mana you spent. A pinger's one damage becomes three. A three-damage burn spell becomes five. A board of one-power red creatures each swings for three. The buff is also strictly one-directional: it only fires when a red source you control would hit an opponent or a permanent an opponent controls, so symmetrical burn and your own sweepers stay lopsided in your favor while your face and permanents take normal damage. The 2/4 body is deliberate underkill, sized to weather incidental damage and small blockers rather than to attack, though the effect applies to its own combat damage too, meaning it lands for four when it does connect. What holds the design in check is that it is a force multiplier: it makes red damage bigger without generating any on its own beyond that four-power swing, so it pays out only in decks already leaning on repeated, incremental red damage and offers nothing to a build that isn't. That conditionality makes it a keystone in pinger, token, and burn shells and a dead card everywhere else.