Return of the Duelist 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, Return of the Duelist is Unlimited.
YGOPRODeck lists Return of the Duelist for these formats: Master Duel.
Among markets shown on this page, the lowest listed snapshot for Return of the Duelist is about $0.10 on Cardmarket (prices change frequently).
