AMEX Offer: 20% Back at Shoebuy.com (up to $20)

Like the title says, 20% back, up to $20 on each card. I had this show on all 3 of my cards, so I'm guessing it's public. This should stack quite nicely with the regular sales they run (currently 25% off) as well as the 15% cashback you can get by going through the portals.

The maximum value you can out of this (without using multiple cards to buy gifts cards) would be a shoe that originally costs ~$133.50. After the shoebuy.com sale, AMEX offer and cashback, you'd be looking at an effective price of ~$65.10, which is a discount of ~52%.

Expires 3/2/16. It doesn't look like it excludes gift cards.

EDIT: Math reboot.....52% off, not 48%.