Change of Heart 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, Change of Heart is Unlimited.
YGOPRODeck lists Change of Heart for these formats: GOAT, OCG GOAT, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Change of Heart appears in 25th Anniversary Rarity Collection (RA01-EN050) at Collector's Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Change of Heart is about $0.02 on Cardmarket (prices change frequently).
