Concentration
 

The skill concentration: it says it allows 2 mana regen (with more at higher ranks of the skill) every turn in combat. But I've realized that this is not entirely true.

For the first 9 rounds of combat I get +2, then at 10 rounds through 19 rounds it's +1. Then after 20 I get zero. Is this the way it is supposed to work? And if so then does this mean that at higher ranks of the skill the same 50% reduction every 10 rounds rule will apply?

Is there anything else that works like this on a 10 round basis?

It's halved because from the 10th round on, the battle is a long, exhausting one and your troops are tired (as per the in-game description). The rage increase will also be slower.

Ok well that makes sense. Where is the in game description located? Does it say "tired" somewhere on the troop description panels or something?

It says so at the bottom of the screen where all the battle statistics are.