You can earn $20 in savings with Amazon simply by linking your Membership Rewards account and then using some points to pay for an order by November 9, 2014.
First you will need to link your eligible American Express card to your Amazon.com account at this link.
Second, add product(s) sold and shipped by Amazon to your cart.
Third, enter promo code SWP20AMR in the promotional code box on the checkout page and pay at least a portion of the order with Membership Rewards points.
Lastly, the $20 savings will be shown on the final page.