Monarch

The Monarch engine turns on Eidos the Underworld Squire and Edea the Heavenly Squire. When either Squire is Normal or Special Summoned, it triggers a chain: Eidos grants an additional Tribute Summon for the turn, while Edea's summon fetches Eidos from the deck. Edea then searches a banished Monarch Spell/Trap when sent to the graveyard, keeping the hand stocked with spell fuel. That fuel feeds Pantheism of the Monarchs, which discards one Monarch Spell/Trap to draw two cards, then banishes itself from the graveyard to reveal three more Monarch Spell/Traps and force the opponent to hand one over — generating both card advantage and graveyard setup in a single card.

The Level 8 Monarchs accelerate the pressure once the Squire loop is running. Ehther the Heavenly Monarch can be Tribute Summoned during the opponent's Main Phase by banishing a Monarch Spell/Trap from the graveyard, pulling a second large monster from the deck to extend the board. Erebus the Underworld Monarch similarly sends two Monarch Spell/Traps to the graveyard on arrival and randomly shuffles a card from the opponent's hand, field, or graveyard back into their deck. Domain of the True Monarchs locks Extra Deck summons entirely so long as the controller runs no Extra Deck of their own, and rewards the Tribute Summoned attacker with 800 additional ATK during damage calculation.

The deck strongly favours going first, where Domain and March of the Monarchs together make Tribute Summoned monsters both untargetable and immune to destruction while simultaneously denying the opponent access to their Extra Deck. Escalation of the Monarchs extends that pressure into the opponent's turn, allowing a Tribute Summon during their Main or Battle Phase and potentially triggering another Monarch's on-summon effect at a moment the opponent is least prepared to answer it.