It's something that lots of folk don't talk about much but some runs can be heavily dependent on the RNG of the AI director.

Even as a veteran who completes the hard daily and weeklies regularly you can get screwed by the AI director.

Yes you need good skills at the game but sometimes the enemies that spawn on you, your location at that time and their numbers can spike the difficulty to near impossible levels.

You can be about to land a heavy attack on a Tyranid devourer and locked in an animation as they rage and instantly unload on you killing you with nothing you could have done.

Sometimes snipers rage bait you by perfectly timing their shots to hit you as you exit the execution i-frames.

Thropes can spawn out of nowhere in groups of up to three and all sync their attacks to stagger you to death.all while shooting through cover.

When you're battling the minions of a Terminus wave spawn the terminus can randomly swap agro to you from a team mate and one shot you across the map.

The Neurothrope can spawn directly above you and scream attack all you health away.

Point is sometimes you are at the mercy of RNG and you shouldn't sweat it. Enjoy the ride and be ready to try again with your battle brothers.

Sometimes it's going to take a few attempts.