Dark 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, Dark Fusion is Unlimited.
YGOPRODeck lists Dark Fusion for these formats: Duel Links, Common Charity, Edison, Speed Duel, TCG, OCG, Master Duel.
A listed print of Dark Fusion appears in Duelist Pack: Jaden Yuki 3 (DP06-EN018) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Dark Fusion is about $0.03 on Cardmarket (prices change frequently).
