Flash Knight is a Warrior Pendulum Normal Monster with Attribute LIGHT, Level 4, Pendulum Scale 7, ATK 1800, DEF 600.
Pendulum cards can sit in the Pendulum Zones for scales as well as resolve as monsters; check both halves of the text when building.
On the current TCG and OCG Forbidden & Limited lists tracked here, Flash Knight is Unlimited.
YGOPRODeck lists Flash Knight for these formats: Duel Links, Common Charity, TCG, OCG, Master Duel.
A listed print of Flash Knight appears in 2015 Mega-Tin Mega Pack (MP15-EN058) at Rare rarity.
Among markets shown on this page, the lowest listed snapshot for Flash Knight is about $0.07 on Cardmarket (prices change frequently).
