In my most recent game, I ran into the mechanic which is I assume used to balance champions, called champion nemesis exos. It was quite shocking at first, because of the general lack of the way to stop the ball of 20 some champions at a moments notice. I ended up losing almost instantly to the home base rush. However in sharp contrast to this, upon reloading- and with prior knowledge of where the attack would be coming from- a single shield generator over a wormhole and some reallocation destroyed the exo with little to no effort. The extremely long warning time for the exo seems relatively pointless in the face of this, as very widespread fortification would be needed to reliably contain the threat, while a single save scum or lucky guess completely neutralizes the problem. This seems somewhat un-conductive to what I would consider enjoyable play, but what do I know.
So what I'm here to ask, is if someone could give me an in depth explanation of how these exos work. Obviously they rush for the home base, but what controls their strength, how often do they form, is there something I'm missing, etc etc. I've read through almost all the 7.--- patch notes god that took a long time and didn't really find anything useful. Also, if there is a way to modify their strength somehow that I'm missing, that would be nice as well. Thanks in advance.