I have located the beast by mere chance. He ganked some random person and I helped them down him. Directly South East from the Northern plain of serendia node (well maybe just straight south) is a pool of water, when some land separating it, and then another small pool of water. He spawns somewhere in this area - the person I saved dragged him a little ways from the spawn location as it ganked them while they ran by. It's a small open area. I have provided a screenshot of the area I found him in.

http://i1021.photobucket.com/albums/af340/dhregin/Rare%20spawn%20pancakes.jpg

Hes south of "Nothern plain of Serendia"- Node in the swamp, he has a big symbol on the minimap.

Location!! location!! location!! I need a Location!!

No location for this guy yet.