From WoWWiki

The Wandering Protector is an Ancient that patrols around Ashenvale forest, covering much of the map as it does so. While friendly to Alliance, it is Hostile to Horde and does aggro. It is therefore advisible for Horde players to keep an eye out, as the Protector has a habit of showing up in the worst possible situations. A large number of Horde players like to return to Ashenvale at later dates and kill the Protector.

Patrol Path

The Protector begins his patrol roughly near Maestra's Post, then heads south. He travels roughly between the middle of the road and the southern mountains and heads east. Upon reaching the river he heads north towards Felwood, only to turn around and follow the same path in reverse. One particular place of note in his path is the hill that is required for the King of the Foulweald quest. The Protector travels very close to it, and can aggro onto players who aren't careful.

History

In Warcraft 3, Ancient Protectors are used as the Night Elves' tower. They're capable of hurling boulders at both ground an enemy air units, although at a somewhat slow pace. True to the nature of almost all Night Elven buildings, Ancient Protectors are able to uproot themselves. Doing so removes their ranged attack and changes their armor to heavy, but also allows them to move into a potentially better placement or survive siege weapons more effectively.