Forgotten Underworld

Released April 10, 2025 — 40 cards

Set code	Card	Rarity
—	Mementomictlan Tecuhtlica - Creation King	—
—	Mementoal Tecuhtlica - Combined Creation	—
—	Mementotlan Angwitch	—
—	Mementotlan Twin Dragon	—
—	Thunder Dragonmatrix	—
—	Thunder Dragondark	—
—	Mementotlan Tatsunootoshigo	—
—	Mementotlan Dark Blade	—
—	Supply Squad	—
—	Thunder Dragon Fusion	—
—	Mementotlan Bone Party	—
—	Thunder Dragon Thunderstormech	—
—	Cross-Sheep	—
—	Magnum the Reliever	—
—	Thunder Dragon	—
—	Thunder Dragonduo	—
—	Thunder Dragonlord	—
—	Mementotlan-Horned Dragon	—
—	Mementotlan Mace	—
—	Mementotlan Goblin	—
—	Mementomictlan	—
—	Mementotlan Bone Back	—
—	Thunder Dragons' Hundred Thunders	—
—	Thunder Dragon Discharge	—
—	Mementotlan Akihiron	—
—	Polymerization	—
—	Fusion Recovery	—
—	Chain Ignition	—
—	High Rate Draw	—
—	Mementotlan Fracture Dance	—
—	Mementotlan Cranium Burst	—
—	Twin-Headed Thunder Dragon	—
—	Mementotlan Ghattic	—
—	Paralyzing Mushroom	—
—	Mementotlan Fusion	—
—	Thunder Dragon Colossus	—
—	Thunder Dragon Titan	—
—	Thunder Dragonroar	—
—	Mementotlan Shleepy	—
—	Thunder Dragonhawk	—