Rakdos Keyrune

The Keyrune cycle answered a perennial weakness of mana rocks: once the board stalls, they become dead inputs producing colors nobody needs. Each one buys its way out of that fate by becoming a creature, and the Rakdos variant leans into the guild's pressure-first identity harder than its siblings. The body it produces is built to attack into blockers rather than hold a line, trading durability for combat reach. That first strike on a one-toughness frame is the design tell: it dictates the math when it swings, winning races and clearing chump blockers before they can deal damage back, but it folds to any incidental burn or ping the turn it animates. The animation is cheap and lasts only through end of turn, which forces a clean either/or each turn: tap it for fixing toward a spell, or pay to send a 3/1 first striker past a blocker. It cannot do both, since a rock that taps for mana is in no position to attack. That is the honest tension the cycle is built around, and the Rakdos one resolves it the way its colors want resolved: black and red prefer a board that keeps attacking, and a mana source that converts into a threat serves that better than a vanilla rock would. None of the Keyrunes warped a format, but as a category they answered the flooded-late-game complaint that dogs fixing artifacts, and this is the most purely offensive expression of the fix.