Double Summon 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 Summon is Unlimited.
YGOPRODeck lists Double Summon for these formats: Duel Links, Common Charity, Edison, Speed Duel, TCG, OCG, Master Duel.
A listed print of Double Summon appears in Duel Terminal 6b (DT06-EN091) at Duel Terminal Normal Parallel Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Double Summon is about $0.15 on Cardmarket (prices change frequently).
