The Slime Serpent mount has been available in game since the launch of Shadowlands, but no one was sure of how to obtain it. Well, thanks to the Secret Finding Discord, the answer has finally been solved!
In order to get the mount, you must:
- Solo the last two bosses of the Plaguefall dungeon, Domina Venomblade and Margrave Stradama, on heroic difficulty or higher.
- Afterwards, a friendly mob named Curious Slime Serpent will appear in the slime pools around Domina Venomblade’s area. Take the portal back up to find it.
- Right Clicking the Curious Slime Serpent will cause you to pet it and the mount will be learned!
Currently, this seems easiest on tank specs that are pretty geared. Most of the dungeon can be skipped, save for the 3rd boss and the trash before Stradama, with stealth and invisibility potions.