Card Shuffle 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, Card Shuffle is Unlimited.
YGOPRODeck lists Card Shuffle for these formats: GOAT, OCG GOAT, Duel Links, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Card Shuffle appears in Dark Revelation Volume 1 (DR1-EN028) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Card Shuffle is about $0.10 on TCGPlayer (prices change frequently).
