Summon: Yojimbo

The Summon cycle's design conceit is that a Final Fantasy summon should behave the way it does in its home game: it appears, does its thing across a few turns, and then it leaves. The Saga chassis carries that structure cleanly. Yojimbo in the source material is a mercenary you pay to fight and who defends you while under contract, and the middle chapters translate that literally: for two full turns, attacking you costs an opponent two mana per creature. That is not a Fog and not a static wall of defense; it is a tax that scales with how many bodies want to swing, so the same effect answers either a single overloaded attack or a wide board. The first chapter buys the contract with removal (exiling a permanent that is already committed or otherwise vulnerable), the fourth cashes out in Treasure sized to how threatening the surrounding boards actually are, and then the 5/5 disappears. What makes the card cohere is that the body and the Saga are not competing for the slot: vigilance means the creature enforces its own tax while still turning sideways, so the defensive chapters and the attacking body describe the same fantasy from two directions. The contract expires on the fourth chapter and the samurai leaves with it, but the Treasure it created and the tempo the deal bought outlast the departure.