The Warrior
In a single life, defeat Fallen in the Eventide Ruins with Arc, Solar, and Void weapons.
Phylaks was ordered to take control of Vex territory on Europa. By defeating her soldiers patrolling the outskirts of the Fallen city, you should be able to discover intel on her location.
"Phylaks takes pride in final deaths. She has defeated many warriors of Light, and she keeps trophies of her victories." —Variks the Loyal