Luck must have been with me...big time. I must have tried it around a hundred times, basically quickloading, enabling critical strike and making the attack, the whole cycle including loading times took no longer than around 10 seconds. I experienced 3 deathbringer assaults, with the last one having max damage.
Oh well if Luke Skywalker can survive a night outside on the planet Hoth, and Han Solo can successfully navigate an asteroid belt in the Millenium Falcon, then I can get a max damage Deathbringer Backstab
