How I get to a card Thunderbringer?
Own a Showdown in the Badlands pack and go to the Open Packs menu, then you should receive Thunderbringer
most cards that are given for free at the beginning of an expansions are not awarded automaticaly in later expansions. For each you need to open a pack of the expansion you want to unlock the card from and it will be guaranteed on top of the cards from the pack
Note that cards obtained that way cannot be disenchanted
Well that’s nice of them. Kinda makes it not very special to own though