Because you're trying to complete it when you only have a few of the early chromie talents unlocked. Sheesh.
And another problem you have is you've already given up and resigned it as 'impossible' for you to beat. With that kind of attitude how the hell do you survive in life? I never even needed the final chromie talent 50%+ move speed/dmg increase to beat it with ages to spare. And I did it as tank :S