Gavel of the Righteous

Most escalating equipment tucks a cost into the growth curve: mana per pump, a sacrifice, a discarded card. This one folds the escalation into its own equip clause, and the loop that creates is the whole point. Each of your combat steps feeds the gear a charge counter, and the equipped creature grows by the running total, so left unmolested it climbs from a modest buff into a double-striking finisher the moment the count hits four. The tension lives in the re-equip clause: shifting the gear to a new body costs three mana or one of its own counters, which means you either pay to preserve the whole accumulated bonus or shave a point off the top to move threats around for free. Crucially, the counters ride on the Equipment, not the wearer, and the growth trigger keys off combat rather than the presence of a carrier, so a kill spell aimed at the current holder touches nothing: the gear survives, its count intact, and keeps ticking upward whether or not anything is strapped in. The double-strike threshold turns that count into a hard breakpoint rather than a smooth curve, so there is a real race between the equipment's clock and whatever removal an opponent trains on the current holder. It rewards a board deep enough that losing a carrier costs only a re-equip, because the stockpile it has built is never the thing dying.