Power Fist

Combat-damage growth on Equipment is a familiar green idea, but this one snowballs on the exact right axis. The counter clause reads back whatever connecting damage lands and stacks it onto the body: hit for four, gain four, and the next swing threatens eight before any other pump. Trample is what keeps that math moving, not by guaranteeing damage through a wall (a stack of blockers whose combined toughness exceeds the attacker's power still eats the whole hit) but by refusing to let a single chump absorb the whole swing: assign lethal to the blocker, and the rest tramples over to trigger the counters. The design pays for its exponential ceiling with fragility rather than a cost gate. The counters live on the creature, not on the Equipment, so the growth is only as durable as whatever is holding the fist; kill the wearer and the accumulated power evaporates, while a removal spell aimed at the artifact leaves the counters intact. That split is what stops a two-mana Equipment from running away with the game: it demands a creature that already connects and already survives its swings, and it rewards evasion redundancy far more than raw stats. In practice it is a trample enabler first and a growth engine second, since the counters do nothing until damage lands, and it pays off hardest on a body that can push through unblocked or shrug off a chump.