Inner-Chamber Guard

The 0 power is the design hinge. Bushido 2 fires whenever this creature blocks or becomes blocked, so its size lives entirely inside combat: it cannot push damage by attacking into open air, but it is far from inert on offense. Send it into a defender and the trigger resolves to make it a 2/4, large enough to kill a small blocker it ran into. The printed 0 power simply means the body does nothing until a combat exchange commits, on either side of it. On defense it spikes to 2/4 the instant something runs into it, then resets at end of turn, trading up against early aggression without advancing your board. The contrast with a vanilla 2/4 wall is not the defensive math (those numbers stop the same one-power attacker and trade with the same large one) but where the toughness is stored: a wall carries its size all the time, while this carries most of it conditionally, paying for the cheap rate by making the swing contingent on a fight actually happening. That contingency is the Samurai design idea in miniature: the keyword pairs a combat-only pump with a trigger that reads attack and block symmetrically, so the guard is equally content eating an attacker or surviving the block when a tougher creature steps in front of it. The number that matters here is never the one printed on the left.