Found it! It left its docking place just as I got there, and I followed it until it stopped again at somewhere in the southeast. It's been there for a while now.
Aboard is Beastcaller Tuk'wa, some conscripts and Pterrorwing.
I got attacked by an invisible troll too...
After looking up the beastcaller I found that the ship will apparently be used in future dailies. So far for the mystery!
