Concentrating Current is a Quick-Play 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, Concentrating Current is Unlimited.
YGOPRODeck lists Concentrating Current for these formats: Duel Links, Common Charity, TCG, OCG, Master Duel.
A listed print of Concentrating Current appears in 2019 Gold Sarcophagus Tin Mega Pack (MP19-EN202) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Concentrating Current is about $0.07 on Cardmarket (prices change frequently).
