go to the dificulty above hard and do the medium boss rush, its just medium dificulty but gives alot more experiance. I've got 400 - 1500 xp from it, it's what i did to move up to hard makes it very easy to get to lvl 50 which should be able to kill hard mode quite well. Though i did use AoE spam party.
I was using Orkillous, Dankur, Abzi and carlso. But i dropped Carlos, he's built like an assasin but with no damage so he ends up pretty useless. Really fast speed he can attack 2 times before the rest can attack once but even at lvl50 he's hitting about 400 meanwhile Dankur can hit everyone for 2000 it just isn't worth useing him.
I have Abzi, and I'm tempted to use him, but he and Lucifur have the same problem of being all fire-based when the Hard level enemies are resistant. That, and Abzi is just extreeemely not my type lmao. I think I got Carlos but haven't leveled him, didn't feel like he offered enough to be worth all that time/effort.
Medium boss rush is definitely helping I think, still feels like I'm climbing a cliff but now making actual progress again. I guess that's kind of how the progress goes here? Up up up, wall, up up up, wall... It can work.