There’s another mount that requires you to farm the boss…
You need someone to play said games to have the card monsters spawn occasionally
You can obtain cards by staying around the Hearthstone tables in Valdrakken. Occasionally, monsters from the cards will spawn and can drop their card as a reward. During these invasions, there’s also the chance of getting Whizbang to spawn.
So you either farm wild cards (aka spending a lot) to get the achievements or hope the hourly boss gives you said cards to collect
Which once again… RNG at its finest