This would be really hard to stat
First it is a different team that you are fighting - and I am not sure that the AI doesn’t reset after each game (I would hope it does).
If the AI does reset (which is should) after a game, then every time you face Kerb it is a fresh instance and all stats restart.
The only way to really do this is in a controlled setting where the AI is using the same team and no resetting after each game ends.
Again, the probability of Kerberos successfully devouring is independent of the other factors that you list (specifically team make-up and previous results). It shouldn’t even matter whether you are tracking every single instance of the AI casting Kerberos against you; tracking whichever ones you track will accumulate an ever increasing sample which, if the troop is working as stated, should eventually converge on 50% (if the RNG is working as it should), or some other figure (if it is not). As long as you are accounting for times when you are protected from devour by indigestible and impervious, your stats should be fine.
One definition of “end game” is: the final stage of a game such as chess or bridge, when few pieces or cards remain.
If you translate that concept to a video game such as Gems of War, only having a few things left to do (some of which aren’t even available yet so it doesn’t even count against you) in order to finish IS the end game.
And when I think about all the progress you have to make to reach that point, and you split it all up into three tiers: beginning, middle, and end… then finishing up the final stages of the game would be getting from 5-10 stars (but like we all know that’s unobtainable at this moment, so it’s not the current end game yet).
So by what you described in your example, plus the definition, I don’t think it’s a stretch to call that progress end game.
Fooo, by your definition then I’m farther along that I thought
I don’t want to be in end game…
Everything except the new kingdom and Silverglade (WHICH torments me daily) is 5 stars or higher. In fact right now I’ve been focusing on getting the 5 stars to 7 with each weekly event. I’m at 15 missing troops and 5 of them haven’t been released I suspect (Myzmer, Ogryn Penguin etc)
However I am only at level 710. So I still feel I have a bit to get to accomplish that aspect.
When you are at “end game” you will know it.