FWIW: For anyone who also plays Guild Wars 2, the cards for 2000 gems count toward this promotion. The xpacs also count, but they're at their normal $30 each right now...if you don't have either of them already, they tend to go on sale for $15-20 fairly often.
Link to the gem card: https://www.amazon.com/Guild-Wars-2-Gem-Card-PC/dp/B009AYOFI0/ref=sr_1_3?keywords=guild+wars+2&qid=1560726843&s=videogames&sr=1-3