Coiling Stalker

Ninjutsu answers a nagging problem for any combat-damage payoff: a creature whose ability only matters when it connects is a liability the moment the opponent can profitably block it. This one sidesteps that by riding in on ninjutsu, swapping in for an attacker the opponent has already declined to block, so it arrives tapped and attacking with a clean path and its trigger fires that same combat. The damage clause seeds a +1/+1 counter each time it gets through, but the target restriction is the load-bearing constraint: the counter can only land on a creature that doesn't already have one. That clause forces the counters outward across the board rather than piling onto a single threat, so the engine rewards a wide battlefield of small bodies over a go-tall build with one juggernaut. It also keeps the payoff from feeding itself: a fresh copy enters without a counter, but once it has one, later triggers must find new homes. A fragile two-power frame and the whole loop hinges on somebody connecting unblocked every turn, which is exactly what ninjutsu exists to manufacture. The interplay is the design: a cheap, evasion-borrowing threat that pays its rent by turning every unblocked hit into a slightly bigger board, spread rather than stacked.