Anyway, i couldn´t care less - the only problem for me for soloing stella em are the mechanics which aren´t working for me like for others, that´s all.
We're talking about running away from the boss after the pull, in which world is that considered as actual mechanic which cant be working same for everyone?
Vampirina has the same speed as Mastarius btw.
Trying to help here: Use Dauntless Spirit or Leibo Protection before or Grendal Minion skill after the pull, if you cannot run away from the boss with the slow on you. Make sure you are already a few meters from the boss right before the pull on the shielding methods.