My reply to another thread:

I'm actually having this exact same problem. I started a new Mi'qote Character who is going full DoM. I have the Lalafell GLA companion and from what I can gather of my 12 attempts of this is that, for whatever reason Path Companions in Lord Errant are loading as an extreamly low level. My path companion hits for 0 or misses. and as soon as the Mages or Amal'jaa use Shadowfall, I instantly fail the mission as my path companion somehow gets 1 shot for anywhere from 350-450 damage.

Having done this quest already I know this isn't supposed to be the norm. The path companion should be at or around your level so that he can actually "participate" in the fight.

I sent in a bug report to hopefully see If they can investigate. My guess, they borked the quest post 1.19 since it has some data relating to ifrit. If a dev is reading, please investigate~