The Lambent Plume is a Keepsake given to you by Hermes and it gives you +1/ 1.1/ 1.2% (rank 1/2/3) dodge chance and move speed for each Encounter you clear quickly.
It’s recommended to do this trophy when you’ve max ranked the Lambent Plume Keepsake to level 3. It will be easier and faster as doing it at rank 1, it will take 20 Encounters cleared quickly to reach the required 20% while at rank 3 it will only take you 17 Encounters.
It doesn’t matter whether you take damage or not, so go on the offensive and go all out. That’s the best way to do this trophy without needing too many repeat attempts.
Follow me on Twitch for streams every day:
https://www.twitch.tv/ferro_r
Hades Playlist: https://www.youtube.com/playlist?list=PLJyGdD4EXPW71hq2ivv970ka0uUBm0KNW
source