Natural Tune 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, Natural Tune is Unlimited.
YGOPRODeck lists Natural Tune for these formats: Duel Links, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Natural Tune appears in Raging Battle (RGBT-EN059) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Natural Tune is about $0.02 on Cardmarket (prices change frequently).
