Re-Fusion is a Equip 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, Re-Fusion is Unlimited.
YGOPRODeck lists Re-Fusion for these formats: GOAT, OCG GOAT, Duel Links, Common Charity, Edison, Speed Duel, TCG, OCG, Master Duel.
A listed print of Re-Fusion appears in Dark Revelation Volume 3 (DR3-EN167) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Re-Fusion is about $0.09 on Cardmarket (prices change frequently).
