Abyss Lich won't move to next phase

Found my first ever Lich, got it down to the health shown, then all it did was look at me whenever I moved and wouldn't move to the next phase. The mound to leave also allowed me to just walk through it. I also tried leaving and entering the Abyssal Depths and nothing fixed it. This area was connected to Estuary from a wild Zana mission

https://i.imgur.com/BbUzIzt.png

Sadly, the fix is required. in the end all i could do was sticking wand in his aaa... back.
Best day ever :C

https://imgur.com/a/m20Ix