Disclaimer: I've already completed the game, so I know what to expect in the final mission.
That said, the fight right at the end was (almost) a complete balls-up. I managed to
kill the first 2 avatars, but then I got pinned down in the open area after the bridge by the constant waves of reinforcements. In the end I took the last avatar down after exhausting all my grenades and with everyone in the squad wounded.
And that was just on Rookie.
So, I'm wondering what the best approach is for that fight, for my second playthrough on Veteran. Should I charge in and try to eliminate each boss as fast as possible, or draw them out on to the bridge? What squad composition would people recommend?
Best Answer
I'd recommend waiting on the side of the bridge opposite where the avatars and enemies spawn. I think that charging in is suicide, you're just asking to get flanked.
Send someone with high movement forward to trigger the avatars and waves of enemies, then run them back. There should be enough cover on your side of the bridge to just set up overwatch and destroy anything that pops into view. I'd recommend using mind control from your Avatar on any organic enemies, use these for scouting and early damage. I brought along 2 psi soldiers which made things quite easy as I just dominated an Archon and a Andromedon. Calling in Blazing Pylons every other turn as well as being able to launch acid is very useful against groups of enemies, and with this setup I had 9 soldiers able to overwatch and fire every turn, which made short work of any enemies. As another tip, try not to use any consumables before getting to this portion of the mission.
The squad I used on commander to win without injury was: 2 psi operatives 2 grenadiers 1 rapid fire ranger 1 gunslinger sniper
Another fun idea: I believe you can dominate a gatekeeper and use it's "raise zombie army" ability, which would make that last mission quite fun.