Wow, this is a fun game. I like the idea of forming an army by defeating foes, and becoming overpowered. You did a MUCH better job than me in making a "defeat foes to become stronger by taking their ability" game. The implementation is clean, simple, and the core idea is executed well. Great job! Has huge potential for expansion.
Also, I managed to find an exploit where you can sit still and let your minions do all the work.
Right-clicking at this point will lag the hell out of the game, lol.