Field Barrier 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, Field Barrier is Unlimited.
YGOPRODeck lists Field Barrier for these formats: Duel Links, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Field Barrier appears in Force of the Breaker (FOTB-EN042) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Field Barrier is about $0.14 on Cardmarket (prices change frequently).
