Crystal Promise 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, Crystal Promise is Unlimited.
YGOPRODeck lists Crystal Promise for these formats: Duel Links, Speed Duel, Common Charity, Edison, TCG, OCG, Master Duel.
Crystal Promise belongs to the Crystal Beast archetype—use that tag when searching for engine pieces and tech options.
A listed print of Crystal Promise appears in Duelist Pack: Jesse Anderson (DP07-EN016) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Crystal Promise is about $0.06 on Cardmarket (prices change frequently).
