Bujin Regalia - The Mirror 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, Bujin Regalia - The Mirror is Unlimited.
YGOPRODeck lists Bujin Regalia - The Mirror for these formats: Duel Links, TCG, OCG, Master Duel.
Bujin Regalia - The Mirror belongs to the Bujin archetype—use that tag when searching for engine pieces and tech options.
A listed print of Bujin Regalia - The Mirror appears in 2014 Mega-Tin Mega Pack (MP14-EN170) at Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Bujin Regalia - The Mirror is about $0.10 on Cardmarket (prices change frequently).
