I agree it isn’t well balanced. At level 57 I am getting green and red enemies, which seems odd. I am still blowing through the trash and heroes, even when they are a few higher levels higher than me, but the purple named bosses are giving me hell. I just went into one of the red vortex things and there were two named bosses level 63. One of them one shot me. They slow me right away so I can’t even try to kite them.
My guess is, they might be a fixed level on normal difficulty, so I might be able to level up and come back to them. Not that I will remember to go back. The catch is, the story line bosses haven’t been that difficult, only the optional ones I am finding impossible.
Just spent a few minutes trying to upgrade relics as well. I think that might help me out a lot, but of course I ran out of money after crafting a bunch of needless stuff (I am trying to get one of each relic).