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.