Got a 10.2 last month, and a 10.1 this month. The simple way is having an antagonist with more than 40% MMR on the mission and hunting them enough to get the entire bar worth of bonus, also fill the kill bonus from grunts. Since you should be killing the antagonist they wouldn't be a threat to your mission, so all that remains is having competent teammates.
In my opinion, the best for this might be Alicia, Hans, Rak, Mikah, but I can see Valeria(depending on the stage) and Harec(if you can end things with one shot), managing to do the job. Doldren is good against antagonists, but his weapon isn't the best for crowd control.