Lswarm

The Evilswarm deck runs on a tight exchange of graveyard resources, spending monsters from it to fuel Evilswarm Kerykeion and cashing them back in as hand advantage. Kerykeion banishes one lswarm monster from the graveyard to recover another, then grants an additional Normal Summon for the turn, allowing the deck to layer two bodies onto the field in a single Main Phase and Xyz Summon with minimal investment. Evilswarm Mandragora supplements this by Special Summoning itself from the hand whenever the opponent controls more monsters, giving the deck a free material that costs nothing from the Normal Summon allotment.

The deck's most important threat is Evilswarm Ophion, a Rank 4 that flatly prevents both players from Special Summoning Level 5 or higher monsters while it carries Xyz Material. In practice this shuts out a large portion of the opponent's Extra Deck options, and Ophion's second effect fetches any Infestation Spell or Trap from the deck each turn, most commonly Infestation Pandemic, which blankets all lswarm monsters in immunity to Spell and Trap effects for the turn. Evilswarm Bahamut adds a disruptive angle by stealing an opponent's monster outright, at the cost of discarding another lswarm monster — a cost that frequently feeds Kerykeion's next activation.

Going first suits the deck well, as establishing Ophion with material remaining creates a soft lock that many strategies struggle to break without their high-Level Extra Deck monsters available. Evilswarm Nightmare extends that pressure by flipping newly Special Summoned monsters face-down the moment they arrive, and Evilswarm Thunderbird can dodge a removal card by banishing itself and returning to the field with additional ATK on the following Standby Phase. Infestation Infection provides a repeatable search at the cost of shuffling an lswarm monster back into the deck, ensuring the hand refills even through a prolonged exchange.