The Daemonhost boss in Darktide is a special enemy. You are NOT meant to attack the Daemonhost. It functions similar to the Witch in Left for Dead. If you don't get near it, don't shoot at it, don't point your flashlight at it then it won't attack you. That means you can just skip the Daemonhost.
However, if you get too close to it or anger it somehow, it will annihilate a group member and then disappear.
If you encounter a Daemonhost in Darktide:
- Don't attack it
- Don't point your flashlight at it
- Don't get too close to it
- Don't run, just walk
When a Daemonhost is nearby in Darktide you will start hearing voices. If you are very close to it your screen will also start to freeze.
If you have an Ogryn with you that has the Shield weapon, the Ogryn can position itself in a corner and just let the Daemonhost attack it while the group kills it.
The video below shows an example of when you encounter a Daemonhost in Warhammer 40,000: Darktide. If you don't anger the Daemonhost it won't attack you.