Welcome Labrynth [BLMR-EN102] Quarter Century Secret Rare Noble Knights of the Round Table Box Set destroy all monsters your opponent's

destroy all monsters your opponent's side of the field

You can only use this effect of "Mermail Abyssteus" once per turn

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When it is Special Summoned by this effect

Welcome Labrynth [BLMR-EN102] Quarter Century Secret Rare Noble Knights of the Round Table Box Set destroy all monsters your opponent'sSet: Battles of Legend: Monstrous Revenge Card type: Normal Trap Rarity: Quarter Century Secret Rare Special Summon 1 "Labrynth" monster from your Deck, also until the end of the next turn after this card resolves, you cannot Special Summon monsters from the Deck or Extra Deck, except Fiend monsters. If a monster leaves the field by your Normal Trap effect, while this card is in your GY, except the turn it was sent there: You can Set this card. You