Mod for Heroes II.

Okay, let's move on to the retreats. Actually, the AI doesn't do this (it doesn't assign a powerful unit to the main role), so when playing against the AI, it often makes almost no difference which Castle you start with. Defeating a Warlock-led army with a Knight and defeating a Knight-led army with a Warlock takes roughly the same amount of time.
As for battles between players, a lot will depend on the map, but with sufficient resources, Paladins are deployed in the first week, while Dragons can only be deployed in the first week on one or two maps. In short, there is no imbalance; all Castles are viable!