Sword of Feast and Famine

The untap clause is what separates this from every other member of its cycle. Each Sword grants protection from two colors and a damage trigger, but Feast and Famine is the only one that refunds the mana you spent to deploy it: connect, and every land you control comes back up, opening a second main phase that can equip again, cast a hand-emptying spell, or hold up interaction you already paid for. That single line turns a beatdown artifact into a tempo engine, because it stacks combat damage on top of a full untapped board rather than asking you to choose between attacking and developing. The discard half is the other edge, stripping the answer before the defender can find a window to use it. And the color pair is the meanest in the cycle: protection from black and from green walls off the two colors that historically hold the most efficient creature removal and the biggest blockers, so the carrier dodges the exact interaction that would otherwise blunt it. The protection also prevents that combat damage from being chumped or traded against those colors, which keeps the trigger firing turn after turn. Three mana to cast, two to equip, and a body bonus that is almost beside the point: the card's value lives entirely in what happens after it hits, and what happens after it hits is that the game tilts and rarely tilts back.