Common unit pool M&M: Heroes VI Guide
Last update: 11 May 2016
The very important thing is common unit pool. Our every city produce some number of creatures - those pull together with others. So, if city A and city B provide 2 angels every, so we'll be able to recruit 4 such units per week (2+2=4). Of course after buying four winged guys, the pool get zeroed, and we won't recruit any of them til the next population - so we have to think carefully about decisions.
Another curious thing is fact, that individual troops do not have to be identical - you can mix them. So, in other words, if we have pretorians in one city (upgraded unit) guardsmen in the second (basic version of the same type of unit), common pool of units is still working - but we can recruit only one type of creatures. It doesn't match in case of troops from different cities - we won't change skeleton into orc.
Dwellings provide army to forts and cities, in correlation with control zone on which they are. Dwellings have three types -with basic, elite or championship units, what is linked to their development level.
Complete list with all unites, their abilities and usefulness on the battlefield, you'll find in race guides.