Nudge to get the ball rolling in The Windhall Chronicles?

I just had a blast mapping the huge game-area. Now I’m looking for a loose thread to pull.
Talking to the wizard seems obvious but I have to get past the obstacle first.

I talked to Midknight who taught me how to battle the Displacer Beast (circle counterclockwise). First I have to find a way to see the transparent Beast though, and I can’t seem to find any paint or something similar.

Ignore the above. I was thinking too linear. Tons of other stuff to do. (Apparently I even missed the wood-elf’s tree on my first reconnaisance.)