This was pretty nice, the character designs were good, decent story, and though the action sequences were a bit shaky, I still enjoyed it. The background work in the very beginning was awesome looking, it really set the tone. Voice acting was great, had no problem with it. Though I have two critical bits of advice, and these are things I'm currently learning as well (before I throw another huge animation to Newgrounds). I think you would profit a lot off of this and make you so much better at establishing/ shooting scenes and animation overall.
You need to practice your moving holds. This moreover applies to 3D animation than 2D. While holding a frame can be perfectly fine in 2D, for a 3D cartoon it's hard, as it makes your characters seem dead. I see you did a little of that with a couple characters in the beginning, but not all. You need to keep them moving, whether it's slight eye movement or head slightly bobbing back and forth. If you look at an actual human, they are never quite still, and we all have different mannerisms. Establish these practices to make your characters unique, and develop them. This will make your animation shine I believe!
The 180 degree rule: A cinematographic rule in which the camera establishes the positions of characters with an "action line". The general rule is to shoot within that 180 degree arc, though there can be exceptions. I saw your 360 degree action scenes and thought you had too many, and needed to establish where your characters are placed.
Theres other small problems, like lack of exaggeration and combat speed, but that's not the biggest priority. Again, you have awesome skill, I just thought that these things were perhaps the most vital information, cause I want to you to go from great to amazing. Look these up on Youtube if need me. Can't wait to see more, peace