Darkmaul

If you happen to come across this page, you can look at the other pages for the long "tutorials" on this, but basically you need to loot 10 Tasty Mawshroom from the invasive mawshrooms in the area. It's not a guaranteed drop, nobody knows the max number you can get in a day but some say 3 can be looted in a day (I think most people feel this rate has lowered significantly in more recent times). You can turn the tasty mawshrooms in one at a time over several days, or all in the same day. Darkmaul is located at 42, 32 in the little section just behind Mauler's Outlook. When you right click to use it near him, you end up riding him for 2 minutes. This has changed since it first started and it does not make you automatically run off anymore. You will be sitting on him and can choose to run or not. You do not need to ride him the entire time. You can jump off immediately and it still counts. After 10 turn ins, you get the mount!

For those who like the visual explanation instead, here is an updated video: https://youtu.be/weBDIGGzaSo