Deck Lockdown is a Continuous 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, Deck Lockdown is Unlimited.
YGOPRODeck lists Deck Lockdown for these formats: Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Deck Lockdown appears in Astral Pack Three (AP03-EN023) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Deck Lockdown is about $0.03 on TCGPlayer (prices change frequently).
