Vinetooth Fang?
It spawns after activating the last pylon at Eastwatch and then runs off into the large cavern NE of said pylon.
You will need a decent amount of cc to kill it.
Why is this in the Revenant subforum?
It’s better to keep your mouth shut and appear stupid than to open it and remove all doubt.
I believe its necessary for one of the collections?
Ghost Yak
You need it for the Glint’s Bastion collection.