I propose not to count the murder of the 2nd boss before patch "Update 21.3.2 - 6:00 AM December 19, 2017th" without providing evidence on the video.
Before the patch, there was a bug with the appearance of The Unseen Spear with a full morale.
Than some of the kinships probably used. To accomplish the challenge, it was enough to kill the boss, don't healling to Unseen Speer.
Would like to keep track of the chronology of clean passes, without using bugs and exploits of the game.
P.S: The challenge on the first boss can still be performed using a bug of instance.