I did them all when they first came out. Assassination was a joke, it's literally dodge this, walk over that, blind when she gets mad. Sub wasn't too bad but I had done it on my DH first as that is what I was playing at the time, so I had the mechanics down pretty easily but I noticed that it was a lot easier as sub than it was as DH. Outlaw took me a fair few attempts as my damage wasn't great, my artifact was trash so it took a long time to get through but eventually did it.
Difficulty levels
Assassination 1/10
Sub 4/10
Outlaw 8/10