Advent Legions (Alert Level)

[Nibelung44]

The Advent legions, aka Alert Level is only increased through timed events, according to the wiki. So not that much from Xcom activities? Meaning that if there is no rubber-band mechanic where the more you kill legions, the more arrives to compensate, would it not be possible to keep things under control by killing as many legions as Advent receives, if not more? I'm curious about that...

[Jadiel]

It is possible, particularly on lower difficulty levels. On Rookie, the aliens initially get 2 points of strength every 14 days. If you can do a troop column or supply raid every week, you can keep global advent strength constant. Additionally, you can remove up to 5 points of advent strength by liberating a region, and you can also (with a bit of luck) get a UFO mission to stop the reinforcements. Once Vigilance is 20 higher than strength, the AI additionally gets 4 points of strength every 21 days, which more than doubles the rate at which you need to do ambushes/raids (this is the rubber band mechanism), but it's still possible.

On higher difficulty levels it's quite a bit harder.