Here is something that is ruining my enjoyment of this otherwise superb game. I have some reason to do a mission 4 levels higher than me, either as a challenge or to unlock an enchant on a ancient relic. I request a random mission from the astropath and my choices are +3 or +5. If I choose 5 then the mission can randomly increase in difficulty in the first phase to +6, which frankly makes the mission too long and lets stupid stuff happen like an Ogryn charge from off screen and kill me with one hit. Later in the series the mission can increase in difficulty AGAIN, to 7 levels higher. That's idiotic. The elites become essentially unkillable, or take way too long to hit and run them to death. I had a 30 minute battle with a single Dark Eldar Chronos one night where I used up all the innoculators on the map fighting it - something like 14 charges.
If I abandon the now obscenely difficult priority mission and start over with a +3, the missions in the campaign NEVER increases like the +5 does. My goal is not met.
For the love of the God-Emporer, just let the priority mission difficulty selector do what is says it will do.