What are the bloodthralls doing?

I was doing the Long Lost Tome quest and came across these bloodthralls. Can anyone tell me what they are doing??

How to open map on Elder Scrolls Online and run

I know it's annoying that Elder Scrolls Online doesn't have a minimap.

I found a workaround. It's not perfect but it works.

Steps:-
1) Press your "W" button and don't release it.
2) Then press "M" button to open the minimap
3) While running, you can straft left, right and reverse. The map will still be there until you stopped running. Once you start running again, the map disappears.

Hope this helps