Overload Fusion 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, Overload Fusion is Unlimited.
YGOPRODeck lists Overload Fusion for these formats: Duel Links, Speed Duel, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Overload Fusion appears in Duel Terminal 7a (DT07-EN042) at Duel Terminal Normal Parallel Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Overload Fusion is about $0.02 on Cardmarket (prices change frequently).
