Base Assault Missions
There are 3 territories where these base can spawn right now and you can have 4 worlds at the same time. There is also a cooldown. It’s at least 1 hr for each separate region. And you have to kill bots in that region to get the bases to spawn (similar to how rivals work).
I find that the bases spawn more frequently if I have 8 rivals in that region. It may just be coincidence, but it seems like the chance for a rival to spawn might supercede a FNIX base takeover.
And I’m not sure if it makes much difference, but I also seem to have better luck when I let the threat level rise.
Another thing I find helps is to rotate regions I’m killing in. Once a base spawns in a region, take it out, level it up, leave it for later, or whatever, but then move to another region and start killing machines there. Once a base spawns there, rinse and repeat.
Lastly, if you haven’t had ‘any’ FNIX bases claimed in any region for a long time, quit out of the game and restart. I’ve done this a few times and the bases immediately started spawning again once I killed some bots.