You don't even know...
DotA is one of my all time favorit games, I have atleast right clicked 1000000 times and tried to select buildings with it and such. Overall the game was good but it was kind of short, last hitting was very easy for me... since I play DotA so much I guess. I kinda wish you could drop items though (not sell, just drop) so you could buy more to combind items when you run out of room.
It was kinda out of Balance though. I noticed that the computer would pop invuln, maddness, and +hp regen on all towers but the madness seemed to be bugged, and the computers also used invul only 1 time on the main building and it was as soon as the main tower died... aka when it wasn't being attacked, and it never bothered to use the +hp. I really did enjoy the combind items and stuff and the pick of being evil/light and melee/ranged.
For a 3ed game this is amazing though, you should make a 2ed ver of this game sometime. I noticed some people saying the NPC was too hard though, the only way it is hard is if you can't last hit anything to get XP.
So my suggestions would be to...
1. Make the computer use ALL building abilitys as much as possible when possible to stay alive.
2. Make it so you can 'drop' items to pick up later.
3. Possibly make a harder mode and in easy mode or something have it so that it is easier to last hit for XP or just get some XP for being around mobs that die.
4. Try to make it longer maybe with new items, some abilitys maybe, and possibly have it so it's kinda a 3v3 with heros giving the NPC some minor advantages since a computer can never compair to a human.
Other than some minor balance issues I think this was an awesome game though, keep up the great work and I hope to see a "The Eternal Battle 2!" or something like that ;D.