I read somewhere that mercenary buildings will be introduced in the next beta. No warlords game I have played used mercenary buildings. However, both the HOMM (Heroes of Might and magic) and Disciples series made pretty effective use of them.
In HOMM (at least HOMM 1 and 2), mercenary buildings had a limited amount of a single unit type. These units could be hired by a visiting army. The number of units available would slowly increase over time.
In Disciples, there were usually multiple unit types available at each building, and the supply of units was inexhaustible, but they so expensive that this was not really an issue.
What mechanic will the B5 mercenary huts use?