Mardu Ascendancy

The reward for going wide on a clan whose whole identity was the alpha strike. Every nontoken attacker fans out into a tapped, attacking Goblin, which means the board you commit isn't the board your opponent expected to face: a five-creature swing arrives as ten attackers. The tokens enter during the declare-attackers step, so they can still be blocked, but they widen the swing past whatever the defender prepared to absorb, and they cost you nothing in cards. That snowball is the carrot. The stick is the sacrifice clause, which folds defense and offense into the same enchantment. Crack it in response to a sweeper and your team picks up +0/+3, turning a Pyroclasm into a fizzle; crack it mid-combat and your attackers (Goblins included) survive blocks that would have eaten them. The tension is that the toughness pump is one-shot, and using it ends the token engine, so the card forces a real read on whether this is the turn to keep generating swarm or the turn to protect what you've already built. It wants a board wide enough that another rank of Goblins matters and another point of survivability swings the race, exactly the go-wide attrition shell a three-color aggressive deck aspires to be. And it can fire the turn it lands: resolve it in your precombat main with creatures able to attack, and that same combat is already bigger than your creatures suggest.