Double Spell 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, Double Spell is Unlimited.
YGOPRODeck lists Double Spell for these formats: GOAT, OCG GOAT, Duel Links, Common Charity, Edison, Speed Duel, TCG, OCG.
A listed print of Double Spell appears in Dark Revelation Volume 1 (DR1-EN161) at Ultra Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Double Spell is about $0.09 on Cardmarket (prices change frequently).
