Originally posted by Zelph:

Yes. Everything in the game is solo-able without cheese.

Boss 1-4 are easy. Yagluth takes a bit of prep, but isn't to bad. I haven't personally made it to the queen yet, but I don't see why she wouldn't also be completely doable with prep work.

I had maxed padded and frostner for the yagluth fight; I mostly face-tanked him and it didn't take very long at all.

As for the queen, there's a bunch of viable builds for fighting her; I'll likely be using the bonemass rush method myself, since it reduces her attack power hugely, allowing you to just lay into her once you let her pin you to a wall( thus eliminating her knockback).