Inspection is a Continuous 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, Inspection is Unlimited.
YGOPRODeck lists Inspection for these formats: GOAT, OCG GOAT, Duel Links, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Inspection appears in Pharaoh's Servant (PSV-038) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Inspection is about $0.02 on Cardmarket (prices change frequently).
