Summon Gate is a Continuous Trap Card.
Trap Cards are normally Set first and can be activated on a later turn, often in response to an action.
On the current TCG and OCG Forbidden & Limited lists tracked here, Summon Gate is Unlimited.
YGOPRODeck lists Summon Gate for these formats: Duel Links, Common Charity, Speed Duel, TCG, OCG, Master Duel.
A listed print of Summon Gate appears in 2017 Mega-Tin Mega Pack (MP17-EN164) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Summon Gate is about $0.10 on Cardmarket (prices change frequently).
