Units are highly versatile. You will be able to control more than twenty of them with different skills and characteristics. It just wouldn't be a true fantasy game without the magic. The guys in Phantagram took that quite literally, and introduced three spell-casting units on each side. The mages have about ten different spells like teleport, speed-boot, concealing, or gathering Mana.
Sorceresses feature some offensive spells like fireball, meteor strike etc.
Units are perfectly balanced, and they all bear marks of the race they belong to. The heroes are a special treat. These guys left a serious mark in the history of the Barsiah continent. They will be the pillars of the story, and you'll only be able to summon them using some highly advanced buildings. Some campaign scenarios will allow you to use particular heroes without having to summon them.