Gather Your Mind 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, Gather Your Mind is Unlimited.
YGOPRODeck lists Gather Your Mind for these formats: GOAT, OCG GOAT, Duel Links, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Gather Your Mind appears in Dark Revelation Volume 1 (DR1-EN142) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Gather Your Mind is about $0.08 on Cardmarket (prices change frequently).
