Secret Blast is a Normal 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, Secret Blast is Unlimited.
YGOPRODeck lists Secret Blast for these formats: Duel Links, Common Charity, TCG, OCG, Master Duel.
A listed print of Secret Blast appears in 2016 Mega-Tin Mega Pack (MP16-EN104) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Secret Blast is about $0.15 on Cardmarket (prices change frequently).
