Adaptive Gemguard

The activation cost tapping artifacts and/or creatures echoes Improvise, the mechanic that spends artifacts on spells, except here the labor buys self-improvement instead of casting anything. That makes this Gnome a board sink that never touches your lands: any artifact or creature idle on a given turn can instead be tapped to add a counter, so the growth scales with how wide you are rather than with untapped mana. The sorcery-speed restriction is what gates it. You cannot flash in growth mid-block, so the tapped bodies are committed during your own main phase, and the opponent always sees the size coming. That turns the ability into an engine-builder's tool rather than a combat trick, and it leans into the fact that the cost treats artifacts and creatures interchangeably, rewarding go-wide artifact shells where the fodder is cheap and plentiful. It is a slow, resilient threat built for grinds: no single activation is a burst, but the counters accumulate as permanent modifications that survive whatever the growth spree cost you in tapped-down defenders. The trade is tempo now for a body that keeps outgrowing removal thresholds later, and white rarely gets a repeatable, land-free way to build a threat one counter at a time. The catch is real: every counter costs two committed permanents at sorcery speed, so the ceiling depends entirely on having a board wide enough to spend without leaving yourself defenseless.