Bojuka Brigand

The growth aggregates: every Ally that walks in, including this one arriving, offers a counter, so the brigand scales with the width of the board rather than its own clock. That makes it a payoff for the Ally enters-the-battlefield engine more than a creature you evaluate on its body, and the design pays for that potential up front by stripping its defense. The can't-block clause is the price: a creature that grows every time you commit another body to the board would otherwise become a wall that punishes the opponent for attacking, so it is locked into the offensive role the rest of the tribe wants anyway. Each counter is permanent and the trigger is optional, which keeps the math under your control across a long game, but the ceiling only arrives if the Ally count keeps climbing. Stripped of the tribe, the brigand triggers once on its own arrival to become a 2/2 that can't block; surrounded by the Allies it was built for, it converts board presence into a single threatening attacker. It rewards going wide while wanting to swing, a tension the no-block restriction resolves cleanly: you are never tempted to hold it back.