Melffy

Unlike most Beast-type strategies that keep their monsters on the field as static threats, Melffy deliberately cycles its members back to the hand — and turns that retreating behaviour into the engine that generates advantage and fuels Extra Deck plays.

The deck's main monsters, including Melffy Catty, Melffy Pony, Melffy Puppy, Melffy Fenny, and Melffy Wally, each share a pair of effects: they bounce themselves to the hand whenever the opponent summons a monster or targets them with an attack, triggering search, Special Summon, or recruitment effects as they go, and then re-deploy themselves for free during the End Phase. This creates a self-sustaining loop where the opponent's own actions supply free searches and bodies. Melffy Wally is the most explosive version of this, pulling two archetype members directly from the Deck in a single bounce. Melffy Footsteps accelerates the opening setup by loading up to four differently named members at once, at the cost of skipping to the End Phase, where those same monsters can immediately self-Special Summon in time for Xyz plays.

The Extra Deck is dominated by Beast Xyz Monsters. Melffy of the Forest searches any archetype card and can lock down an opponent's monster each time a Melffy bounces off the field. Melffy Mommy stacks materials to gain progressive battle protections, while Joyous Melffys enables direct attacks or tears itself apart to flood the board from the Graveyard. Merry Melffys and Melffys' Joyful Surprise round out the Extra Deck with bounce removal on summon, giving the deck genuine disruption to supplement its resource generation. The strategy rewards patience, as many of its best triggers activate on the opponent's turn rather than the player's own.