During the base defense you get the option of using a terminal to flush the vents, which also causes some damage to the base. I got the first two out of the three. No big deal, I will just have to fight a few more enemies. I also had a 5 turn countdown that says you need to survive turns (I assume this means reinforcements stop after 5 turns if you are still alive and you can clean up the rest in however many turns). When 5 turns were up, I "failed" the mission even though I was winning. I know base defenses are still being worked on at the moment, I just thought I would pass it on. I also wasn't certain about the "vent overload" or whatever it was called. Like if you get one are you then committing to get all three or you fail the mission?