Owl's Head Sewer

Hoping some of the Avatar's here who have found success can share any tips for the Lich in this dungeon. There was one video I found on it a couple months ago but cannot find now. Thinking @Vero or another elite may share.

Group- 3 Avatars. (2 healers around ≈80-90 level, 1 fire/range ≈120 level)

Current Strategy -
I believe the Lich has the 'Near Power' attribute so we try and kill the adds first. We get up on the first tower, kill the skeletons that climb up with us, jump on the wall and try and kill adds before dying. We have seen the boss hit for 600+ on one shot so death can come quickly.

We almost finish killing all the adds (Usually there is 1 ghost still up) but than we get respawn before we can even start on the lich...

Any help would be appreciated!