Tldr
Warlock and the Lost meet up on Avenger defense mission, and my brain froze like my PC when a Gatekeeper enacted a mass resurrection of a large collection of fallen Lost and for my sanity required me to redirect every available resource to the Gatekeeper to not lose the campaign by virtue of locking myself out of the game if the enemy Gatekeeper survived.
Ended the mission with, if I recall correctly, 355 kills of which most of them where caused by the Gatekeeper who effectively doubled the body count
More detailed account:
spoiler
On a Ironman Commander difficulty chill run, decided to take my time with the Chosen and deal with them as a pre-final mission victory lap.
So leave them to their devices and deal with the Avenger defenses as they come.
This ideal changed very quickly once I was accosted by the Warlock with "The Lost" Dark Event.
So I take it slow as every 2 turns I have to deal with the 4 exploding ghosts the Warlock likes to pop into battle. This forced me into a defensive position and had my Reaper scout and move towards the cannon while snipers pick off what I could in between down time.
Of course, I could not always get the ghosts so they explode and draw in Lost.
So I end up digging in around the Avenger with the rest of the team setting up a "Kill Zone" in a nice convenient pass.
By the time I gain control of the situation and start working towards finishing up the mission, I am sitting with the pass with a graveyard of probably about 100 Lost corpses lying about.
I move the rest of the team forward, taking enemy forces as I advance and on enemy turn, a Gatekeeper, spotted earlier but not finished as I had assigned it a "lesser threat" moved into range towards the Lost graveyard. Needless to say, I could not finish it with what little overwatch I had in place and it did its psionic wizardry.
Game hangs for quite a while and eventually comes to as it is now in control of an army of Lost. My turn has a new objective now that forces me to ignore everything else to kill that Gatekeeper as I cannot handle the thought of having 100+ enemies take their turn if I fail.
Fortunately I was able to kill it with every explosive and ability I had on hand and experienced an equally cathartic release of emotion as my PC was catching up to the sound of the hordes dying out in the ensuing psionic backlash.
Needless to say, I was able to complete the mission with 355 kills to the mission - which the game counts revived enemy zombies as a "kill" if they go down
