Rainbow Bridge 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, Rainbow Bridge is Unlimited.
YGOPRODeck lists Rainbow Bridge for these formats: Duel Links, Common Charity, TCG, OCG, Master Duel.
A listed print of Rainbow Bridge appears in Battles of Legend: Crystal Revenge (BLCR-EN055) at Ultra Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Rainbow Bridge is about $0.12 on TCGPlayer (prices change frequently).
