Here you go.

Perhaps we all missed this last night, but Amazon has a link to the terms of the promotion on Hearthstones page.

http://www.amazon.com/Blizzard-Entertainment-Hearthstone-Heroes-Warcraft/dp/B00P77ZAN8/

There is one important one that can make everyone rest easier.

1. Limit one per customer per app, in-app item or other product subject to the promotion, other than for in-app items designed to be purchased multiple times (such as in-game currencies or extra lives).

As packs are designed to be purchased multiple times, it seems we are supposed to receive the bonus each time!

You're right, my bad, I linked it above now but it is here.

The Hearthstone download is here

https://www.amazon.com/Blizzard-Entertainment-Hearthstone/dp/B00P77ZAN8/ref=sr_1_1?dchild=1&keywords=Hearthstone&qid=1632170033&s=mobile-apps&sr=1-1

Seems to still be there