The Swindler card says:
Each other player trashes top card of his deck and gains a card with the same cost that you choose.
We've encountered a situation when Swindler stumbled upon Spoils card, which is not in the supply, and hence does not have a cost defined. What is to be done then? The owner of the Swindler would of course be happy to give Ruins to the affected player instead, but I am not quite sure what the right way to resolve this is.