I want to chime in here, because some comments I want to make are in line with some of the OP's comments.
Almost off topic; I think you have to learn to utilize oak, his ability to inspire troops is crucial to his play...Obviously a counterpart to Erebus, but one of "honor" as opposed to "deceit", I don't think it's as effective, but it is pretty useful.
The problem I'm having, is that I think Erebus is overpowered a bit, honestly, his ability to decimate troops with charm, bat swarm, and mist makes him an incredible force. The problem with that is...That you are in part reliant on your followers, (catapultasauri and giants leap to mind) and with erebus ability to move in and out of battle quickly, the ability to tear apart followers, and modes of attack that make him unassailable, it often takes a demigod to kill him, where others are threatened by many of the followers, and he's hard to hit. Granted that's a "character" element, but it may have a problem when juxtaposed with gameplay. I think in a broad way the design is good, but a team of three or four erebus against a more "balanced" team will likely win. Erebus getting away from most followers is an easy task, except those that are airborne or have missle weapons. Which are actually a little rarified in the game.
Which brings me to a second point, game balance, there needs to be a reason to choose a demigod. The characters are variated, and that does lead to propensity and facility, but in an overall way I think it lacks some balance...Perhaps a lot of balance. The example I posed before came up in a game I played, in which the opposing team was four erebus, and I think an unclean beast. It was complete decimation. And the other team was well "balanced" I don't recall exactly what I was playing, nor the entirety of the team I was on, but erebus ability to move can be unassailable or very close.
All of the demigods have character and are compelling, but in terms of gameplay it's obvious, in the available mode of play, that one demigod does not equal another, which is good, but...The idea that you would need a variated team to make your assault makes for a better game. But that doesn't seem to be the case. I think there are more and less effective demigods at the moment. The complexity of the characters makes for really compelling characters, but a difficulty in terms of balance, and I think this is an issue. I don't want the demigods to lose their depth as characters, but I do want balance as well.
Also, game modes. I feel like I'm playing Control point maps a bit at times, control the neutral gateways and you win. It has more depth than that obviously, but it runs the risk of becoming like granary in Team Fortress 2..running back and forth overturning crucial neutral flags. Repetition may be the mother of learning, but it can get tedious, and once people see the importance of those particular flags, the repetition may ruin the gameplay type. I think I read that you intend other modes, which I'm all for (considering what I'm thinking about the gameplay modes now).
This, brings me to another TF2 comparison...the maps need asymmetry. CP maps don't get much play anymore in TF2, and the reason is repetition, people have mastered those modes. Presumably you know this, but hopefully the comment is useful.
Some positive comments...The avatars and settings are beautiful, the characters have depth and a fair variety of them, and the complexity of power maneuvers makes the game engaging.