Spire's Masked Merchant

All cards in all hands have sell 3 (Exile this card to target merchant, then create three gold artifact tokens
with "Sacrifice this artifact: Add one mana of any
color to your mana pool. Sell only as a sorcery".)
All cards exiled with Masked Merchant have
purchase X, where X is the card's
converted mana cost (Cards with purchase may
only be cast by sacrificing Gold or Treasure tokens
equal to its purchase cost. Any player may cast a
spell with purchase except whoever sold it.)