Galaxy Wave 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, Galaxy Wave is Unlimited.
YGOPRODeck lists Galaxy Wave for these formats: Duel Links, Common Charity, TCG, OCG, Master Duel.
A listed print of Galaxy Wave appears in Order of Chaos (ORCS-EN062) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Galaxy Wave is about $0.21 on TCGPlayer (prices change frequently).
