This clever loop hinges on Marina Vendrell acting as the mechanical engine to repeatedly lock and unlock the Fractured Realm half of Mirror Room // Fractured Realm. Because Fractured Realm features a powerful static ability that causes your triggered abilities to trigger an additional time, unlocking that door yields two token copies of Tidewater Minion instead of just one. From there, you use one Tidewater Minion token to untap Marina, lock the door back down, and use the second Tidewater Minion token to untap Marina once more, resetting the process to flood the board with infinite creature enters-the-battlefield triggers and an army of token copies. While Yarus, Roar of the Old Gods is part of the broader deck's synergy, this precise loop relies entirely on the precise door-manipulating cadence between Marina and the Mirror Room // Fractured Realm token generator, fueled by the versatile untapping power of the Tidewater Minions.