Turtle Oath is a Ritual 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, Turtle Oath is Unlimited.
YGOPRODeck lists Turtle Oath for these formats: GOAT, OCG GOAT, Duel Links, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Turtle Oath appears in Magic Ruler (MRL-066) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Turtle Oath is about $0.05 on Cardmarket (prices change frequently).
