Can be tamed.
Located in The Placid Spring, Tiragarde Sound. The Guardian of the Spring is normally friendly but can be tamed if you use the toy "N'lyeth, Sliver of N'Zoth" while in War Mode. This version of the Guardian is a vignette NPC at approx 61,52 that can be ridden for 40 seconds. If you ride it to Roan Berthold at approx 67,52 you'll be dismounted and receive a lootable chest. A version of the Guardian with a different NPC ID will appear there for a short time.