How many cards can I auction at once?

If you are a current XL player, you may have up to five (5) active auction cards in one 24 hour period, whether or not the cards sell. If you accidentally list one in auction, you can de-list it and re-list another card without the de-listed card counting toward your 5.

If you are not an XL player, you cannot sell cards in the auction houses, though you may purchase from them as much as you'd like.