Promotion details, per the product page:
$20 Credit Plus Amazon Exclusive Dog Tag Pack and Limited Edition Bonuses
Order Battlefield 3 – Limited Edition for Xbox 360 or PS3 and receive a $20 promotional credit plus the Amazon exclusive Dog Tag Pack as well as the Battlefield 3: Back to Karkand expansion pack for free. Promotional credit good toward the purchase of items shipped and sold by Amazon.com (certain exclusions apply, including gift cards, Kindle books, MP3s, and video rentals and downloads). We will send you a promotional code via email within two days after your order ships. The code to access the exclusive content will be emailed to you within two days after your order ships. Limit one per customer. The Limited Edition content will be available in the product packaging. This offer will be extended to all existing pre-orders. Amazon reserves the right to change or terminate this promotion at any time. Offer valid when shipped and sold by Amazon.com.
Pre-load Today, Play October 25
Purchase Battlefield 3 – Limited Edition (PC Download) and you will be able to pre-load the game anytime between now and the minute the game is officially released at midnight on October 25, 2011. This means that customers will be able to download “Battlefield 3 – Limited Edition” and get their activation key in preparation for the October 25, 2011 release. Customers who have pre-loaded will be able to play immediately on October 25 at Midnight Pacific time when Electronic Arts turns on their activation servers. Customers who order before October 25, 2011 will still receive the Amazon exclusive Dog Tag Pack for multiplayer use as well as the Battlefield 3: Back to Karkand expansion pack for free. The expansion includes four legendary maps from Battlefield 2 boldly re-imagined in the Frostbite 2 engine, as well as Battlefield 2 weapons, vehicles, and unique rewards. The code to access the exclusive content will be delivered to you with your game download. Limit one per customer. Amazon reserves the right to change or terminate this promotion at any time.