I'm not sure if you're constantly reloading, but frankly the odds of you getting 3 umberdoths by turn 100 is very low.
First they have to be on the map (I haven't seen enough of them on map to have 3 by turn 100 in normal settings games, on Ridiculous).
2nd, you have to be extremely lucky to beat slightly more than Vegas odds (above 56% fail chance) to get one, let alone 2 more unless you're reloading. If you have to reload, it doesn't count - and since the spell is level dependent, I think this may be the case here.
As per auto-complete battles --
There is a massive problem with them, so much of a problem that you should never use it if you want to keep your units alive.
The damage given, and the units used, seems to be completely off of what a normal battle would produce. A lot of the damage will go to the unit 'at the bottom' of your army list. That's rarely the unit that gets killed in a non-auto fight.
I've had archers wiped out by 'weak' enemy army compositions even though I had 4 melee units of my own in the army. Somehow, according to the auto-complete fight, the entire enemy army teleported past every other unit (not even a scratch) and surrounded my archer unit to kill it.
Heros seem to live a lot longer than they should, even though when they are at very low health (as in got killed and got teleported to the city sort of low health), my units normally wipe out the heros in one shot (even berserked units head towards the totally weak heros). Somehow in auto-completed battles, those heros can dish out maximum damage, but take none themselves until the rest of their army is gone.