Barbed Batterfist

Equipment has always carried a tempo tax: the weapon sits inert until a creature shows up, then charges you again to suit that creature up. For Mirrodin! collapses those two beats into one. The card enters and immediately spawns a 2/2 Rebel already wearing the gear, so it reads less like an armament and more like a body that leaves a reusable weapon behind when it dies.

The +1/-1 aims the whole design at a single line of play. That Rebel token swings as a lopsided 3/1, and any later host trades durability for reach, a bargain that rewards the aggressor and punishes the defender. Bolt it onto something you meant to keep alive and you have made it easier to kill, so the fist behaves like ballast on defense and a spear on offense. That toughness penalty is the concession funding the low cost: no clean stat bump like Bonesplitter, which hands out raw power with no strings but does nothing until a body is on the board to wield it. This design front-loads the aggression and the token instead of the sheer numbers, and it accepts that it will never harden your board in exchange. It is gear built for a player who is already swinging, pushing damage before the arithmetic of that lost toughness starts working against them.