Living Infernal Core
Location: The Nighthold
Drop Chance: Normally 1%, now 6%.

With this, you can summon your Fel Fire Infernal, which serves as a – more or less – loyal mount when you stomp through the vastness of Azeroth on the fel-green monstrosity. For warlocks, this is quite a flashy mount, wanting to showcase their dominion over demons – but all others should find a nice addition to their collection here.
As a small bonus, you can also obtain the toy of Jaraxxus’ golden Hearthstone card from Gul’dan. So, a visit to Gul’dan is doubly worthwhile since the chance for this toy is also drastically increased.
Of course, you can also use the “Collector’s Bounty” bonus for all the other mounts you have always wanted to acquire. This list is just to show a few options and reveal incentives that might guide your selection of desired mounts.
If you don’t want to farm mounts, you can also buy some for gold. We have listed the most expensive mounts in WoW here.