I've beaten all the levels for each difficulty, normal, nightmare, and hell. I'm current'y on floor 93 in the infinity tower, and it gets waaaay harder as it goes on. Each floor for me has 4 bosses that attack you at the same time.

Normally I upgrade my armor and sword, but thats because I don't have a legendary ring for my tier yet. If I were you, I would only be upgrading rare or above at best, try not to waste money if you can help it, but to get further on it can be quite the grind for levels and money.

Wow, that's crazy.... To think having 1 million+ dmg would still not be enough to  clear it :P. Is there a limit on enchanting stuff by any chance?

And yeah, it is a HUGE grind for me currently, in the nightmare areas. I thought   having 24h unlimited stamina would be a huge advantage, but it really doesn't    seem to be the case.