Valhalla, Hall of the Fallen [SR05-EN029] Common BT6-042 it may digivolve into [Quartzmon]

it may digivolve into [Quartzmon] in your hand or under one of your Tamers and reduce the digivolution cost by 3 instead

)[Your Turn] When Digivolving one of your Digimon into a Digimon card in your hand with [Tyrannomon] in its name， you may suspend this Tamer to reduce the memory cost of the digivolution by 1

Tactical Masters

If you control a "Harpie" monster

Valhalla, Hall of the Fallen [SR05-EN029] Common BT6-042 it may digivolve into [Quartzmon]Set: Structure Deck: Wave of Light Card type: Continuous Spell Rarity: Common Once per turn: You can Special Summon 1 Fairy monster from your hand. You must control no monsters to activate and to resolve this effect.