Mage's Curio Shop

At the Beginning of each opponent's
end step you may have that player choose to
discard a card from their hand and create X
treasure artifact tokens into play under your
control and they draw a card for color
that card has, where X the colorless cost of
that card.
"What?! How much is that, you say? If you
have to ask, then you can't afford it!"
- Professor Quink