Target opponent exiles the top X cards of their library. You may cast any number of nonland cards with converted mana cost X or less from among them without paying their mana costs.
9/20/2014 You cast the cards one at a time as Villainous Wealth is resolving, choosing modes, targets, and so on. The last card you cast will be the first one to resolve. Ignore timing restrictions based on the cards’ types. Other timing restrictions, such as “Cast [this card] only during combat,” must be followed.
9/20/2014 Because you’re already casting the cards using an alternative cost (by casting them without paying their mana costs), you can’t pay any other alternative costs for the cards, including casting them face down using the morph ability. You can pay additional costs, such as kicker costs. If the cards have any mandatory additional costs, you must pay those.
9/20/2014 If a card has in its mana cost, you must choose 0 as the value for X when casting it.
9/20/2014 Any cards you don’t cast this way will remain in exile.