Minor Heroes are typically unit Champions, or fighters of some ability but little renown. They follow all the rules for Heroes as per the TTS! core rules
A unit can only have 1 Minor Hero at any one time. If a rule or spell adds a hero marker where one already exists ignore the result.
Major Heroes are mighty warriors to whom soldiers aspire, and will follow into battle. They follow all the rules for Heroic Generals as per the TTS! core rules
M² is set in a land of Magic and Might. As such Heroes have a much larger role to play in our battles therefore any General can be Heroic
Legendary Heroes are always named and unique. Only 1 can be fielded in an army. They follow all the rules for Heroic Generals. In addition they always have a special rule included in their profile. Some Legendary heroes must be attached to their unit.
Wizard is a characteristic that can be given to any general. The general can then cast spells in addition to their normal abilities.