Warhammer 40,000: Darktide

Easiest way to complete this is waiting until at least early mid-game (over level 10) and having at least one Ogryn. Let the Ogryn hold the aggro of the daemonhost with a shield and everyone else focus on doing as much damage as possible. The psyker brainburst will do large chunks of damage so having multiple in the party can prove useful.

As a solo, running quick matches on at least the second difficulty will increase the odds of having daemonhosts in the match and from there it's just chance if the team you are with will be coordinated enough to take one down

The Chainsword will be your blessing from the Emperor to help you with this one. The special attack from revving it will make your next melee attack do a significant amount of damage to the Daemonhost. Multiply that by several people with one, or just doing their best damage attacks, and you’ll be able to kill one of these things in less time than it takes it to drain the life out of a downed teammate.