Things I liked:
First of all you made a god damn MMO. Props to you for doing that, I couldn't even begin to imagine how much work that would require out of someone. Once I figured out what I was doing and got into the game, everything felt fluid. Combat was simple and easy to understand but required also a decent amount of understanding to perform effectively.
Things that could be better:
The first time I tried playing everything was janke. It fixed itself on the second go through but the first time I couldn't attack and the movement and maps were all messed up. Afterword's it worked better. The combat has a fun increase gain but once you gain a few kills even if you stand still you still hurt yourself as your fireball just gets too big. In addition, despite being multiplayer, there really isn't any reason for it to be multiplayer. Some mechanic or reason why greatly improve it I imagine.
Overall, a real technical feat to be happy with!