What build did you finish the game with? As far as I can tell there are only 2 or 3 pieces that can possibly beat the game, because only those pieces scale exponentially. Grey goo+Gold Goo, Hellhound...???
With Hellhound alone I eventually had almost every space filled with hellhounds, and still couldn't get past level 10. That makes every other "good" piece look worthless.
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It seems like one of the only builds that can do the 1000 dp/turn that you need to beat the 10th boss. If you got enough webbing you could theoretically do it with the Arakh, but I think your damage would accelerate too fast and you would end up facing the final boss without enough webbing to consistently deal 1000+ (you need 10 contiguous webs+arakh), or you would accelerate too slow and die on an earlier boss.