Soul Token is a Fiend Token.
Read the full card text for activation timing, costs, and once-per-turn limits before you slot it in a deck.
On the current TCG and OCG Forbidden & Limited lists tracked here, Soul Token is Unlimited.
YGOPRODeck lists Soul Token for these formats: Duel Links.
Soul Token belongs to the Chaos archetype—use that tag when searching for engine pieces and tech options.
Among markets shown on this page, the lowest listed snapshot for Soul Token is about $0.99 on eBay (prices change frequently).
