Never managed to kill him in Eleum Loyce due to not having a weapon to stunlock him, but I got him in Brume Tower cuz you can just run in front of him once he guns it for the stairs.
Okay screw y'all guys. This guy is amazing. This is what invader NPCs should've always been. This is the most cleverly designed enemy that actually used the area to fight you, which is what the disadvantaged invader should do. This is peak NPC design.