You need 100 Play mode wins
Recently, Blizzard announced that a special flying card mount would be available for Heroes of the Storm players who completed a certain task in Hearthstone. What’s do you have to do, you may ask? Only win 100 games in the Play mode. Wait, 100 games?!
While it’s not exactly a difficult challenge (just play game after game and you’ll eventually bruteforce it), it’ll take quite a bit of time if you haven’t already been playing Hearthstone for quite some time. Either way I’m nearly there, so I’m just go get some games in this weekend. If you’ve already met the requirement, you just need to log into Hearthstone to pop the Easy Rider achievement.