Tuning 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, Tuning is Unlimited.
YGOPRODeck lists Tuning for these formats: Duel Links, Common Charity, TCG, OCG, Master Duel.
A listed print of Tuning appears in 25th Anniversary Tin: Dueling Mirrors (MP24-EN055) at Prismatic Secret Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Tuning is about $0.06 on Cardmarket (prices change frequently).
