I did the challenge in 90 minutes by doing LASO New Alexandria. For AGES, maybe an hour, I just flew around ignoring the mission and killed over 170 banshees and about 12 Phantoms. This worked well for me, what did those of you who did this challenge do to get it?
Did it in about 40 minutes with a friend on N.A. Quite easy, just flew around blowing stuff up
Legendary ONI Sword Base - all skulls except tilt mythic iron black eye blind on, hijacked a wraith and blew up phantoms at the AA gun. Each one scored 7200 points, it took 45 minutes. Quick and painless.
Did the same on NA but i didn’t go full on LASO.