Fusion Armament is a Normal Spell Card.
Spell Cards are usually activated from the hand on your turn unless their type gives another timing window.
On the current TCG and OCG Forbidden & Limited lists tracked here, Fusion Armament is Unlimited.
YGOPRODeck lists Fusion Armament for these formats: TCG, OCG, Master Duel.
Fusion Armament belongs to the Polymerization archetype—use that tag when searching for engine pieces and tech options.
A listed print of Fusion Armament appears in 25th Anniversary Tin: Dueling Mirrors (MP24-EN105) at Prismatic Secret Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Fusion Armament is about $0.88 on Cardmarket (prices change frequently).
