Blizzard did explicitly mention that they added a preview of the wing boss to the break floor in their hotfix notes.
This list is missing bosses.
You've obviously not fought Elder Longbranch yet. If you can't burst through Bounty of the Forest you can't kill him. He's a real PITA for Blood DKs.
One comment on the boss Warden of Sould. The image above can be mistaken for a body-less head, whereas he's actually a Lizard like being. His own page, linked from the nasme below his image shows this.
Maw of the Maw and Writhing Soulmass have similar, but not identical holograms:
The weird thing is that I found the two remaining bosses in only 3 tries. The pictures appeared at level 3, and boom! I got it. Only one time I had to restart.