Aquaman: let the library answer the attack

Arthur Curry, King of Atlantis leads a Simic (green/blue) Commander deck where declaring an attack can bring another creature into the fight. His Call the Tide ability reveals cards from the top of your library until a creature card appears, puts it onto the battlefield tapped and attacking, and places the other revealed cards on the bottom in a random order. The Aquaman cast surrounds this central action with rewards for creatures entering combat that way.

• CALL THE TIDE: Reveal cards until you reveal a creature, put that creature onto the battlefield tapped and attacking, and put the rest on the bottom of your library in a random order.
• THE KING'S ATTACK: Arthur Curry, King of Atlantis calls the tide when he attacks. Your creatures that entered attacking this turn get +1/+1 and have trample while his ability applies.
• CLEAR THE WAY: Mera, Queen of Atlantis taps a target opposing creature whenever one of your creatures enters attacking; it stays tapped during its controller's next untap step.
• READ THE CURRENT: Nuidis Vulko, Royal Advisor scries 2 at the beginning of combat on your turn and draws a card whenever you Call the Tide. Atlan, the First King draws a card whenever one of your creatures enters attacking.

An arrival in combat has its own rewards

A creature put onto the battlefield attacking has entered combat without being declared as an attacker. That distinction matters here: Atlan and Mera reward the entry, but the new creature's own attack trigger does not fire merely because it arrived attacking. Arthur's bonus applies to those arrivals for the current turn, and Call the Tide has no instruction to sacrifice or return them afterward.

Karathen, Leviathan of the Trench offers a substantial arrival with trample, ward for four mana and an entry effect that returns up to two opposing nonland permanents to their owners' hands. Atlanna and Orm provide additional attack-triggered calls. This Aquaman Magic Proxy deck suits players who enjoy sea creatures, library preparation and a combat step that can grow as its abilities resolve. Vulko's precombat scry makes the next creature worth planning for.

A 100-card Commander deck plus 3 tokens, with the existing Bracket 4 designation.