So, I've been having fun with the new heroes. I can't say that it has worked out for me; I've just been noobing around with them and watching my enemies catch my armies with their pants down. Everywhere I send my heroes, the enemy's Barbarian is somewhere else eating the normal armies.
Anyway, I'd like to suggest a balance change for the Ambush ability. Currently, the Barbarian hero is a god on small maps, and useless in mid-late game on anything else. Throw a few ghosts together with some fodder, and you can kill the Barbarian in one try (or two if you're unlucky). This seems a bit unbalanced. Now I don't have the solution to the Barbarian on small maps; the only thing I can come up with is banning him from certain maps (and I'm not suggesting that yet because I believe we will find a better solution). However, I think we ought not to be able to render him useless with Ambush. Ambush should not kill 5 hit points in one shot. Originally it killed 2 (one unit).
My proposal is to make a successful Ambush roll remove 3 hit points from the enemy unit before normal battle rolls. This would mean that a Barbarian who has 4-5 HP is not instantly killed. However, the Assassin and/or critical stacks would still be effective at their jobs, now needing 2 successful rolls to kill a well-leveled Barbarian.
There also needs to be a change in the tooltips and descriptions of the Ambush ability everywhere they exist (reflecting the change to the ability).