I had some very general ideas for heros if anyone wants to run with them:
Bandar Log - How about a size 4 King Kong type monster with trample. The nation could certainly use a melee heavy hitter IMO
Atlantis - I always thought that the folks of this nation would have some high tech given the myths you read about. Some sort of clockwork robot hero or a mage that could summon one of the construction tree mechanical units as well as giving them a powerful bonus in combat to represent there ability to repair them (regen for units they lead or some such) might be interesting.
Ermor - Having a Dr. Frankenstein type hero working for this nation would be quite funny. He could summon random undead that would get a set of random afflictions and/or abilities. So you never know what you are getting
Vanheim - I always thought that this race should have a female seduction hero given the fact that illusion is one of their primary magics.
I'll try to post more ideas at a more decent hour
