Cryptozoic Entertainment is another company that has a No Purchase Necessary offer for US residence only. They have a neat website that details which of their products are available for No Purchase Necessary entry. Similar to Topps and Panini, you will have to mail in a postcard to participate in any of their No Purchase Necessary offers.
For full details on how to participate and rules please click on the link below:
https://cryptozoic.com/pages/special-insert-card-official-rules