Revival Swarm 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, Revival Swarm is Unlimited.
YGOPRODeck lists Revival Swarm for these formats: TCG, OCG, Master Duel.
Revival Swarm belongs to the Battlewasp archetype—use that tag when searching for engine pieces and tech options.
A listed print of Revival Swarm appears in Battles of Legend: Hero's Revenge (BLHR-EN041) at Ultra Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Revival Swarm is about $0.13 on Cardmarket (prices change frequently).
