elderflame collection how do you do a finisher?

12345678910

I got the elderflame collection today. i got all the upgrades for the assault rifle i forget the name, not the shotty not the sniper the other one, i bought all the upgrades with my earned radiant points. but i haven't seen the finisher yet and i have kill a bunch of people with the gun since i bought it. how do i set it so i see the finisher?

TobeySK

You need to kill the last enemy in that round

12345678910

thanks i found that out since last time. i wish it was for every kill.