Level Modulation 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, Level Modulation is Unlimited.
YGOPRODeck lists Level Modulation for these formats: Duel Links, Common Charity, Edison, TCG, OCG, Master Duel.
A listed print of Level Modulation appears in Dark Revelation Volume 4 (DR04-EN099) at Common rarity.
Among markets shown on this page, the lowest listed snapshot for Level Modulation is about $0.10 on Cardmarket (prices change frequently).
