Taken about 2 years but finally got all badges.
Grandmaster score chaser was the hardest one for me. Had to complete with 7 challenges to get it. Doom slayer was tough too but when I got the right build I absolutely smashed yog for it.
Nice! how did you complete doom slayer? with only the 1 challenge, or with multiple? I believe I completed doomslayer with only the necessary challenge and was able to do it rather easily since I've beaten the game with 6 challenges. Admittedly, I forgot that not destroying the demon spawners allows harder enemies to spawn. I was so confused to see the scorpions, and evil eyes around lol.
Yeah I only had badder bosses on for that one. And you're right, not easy with the extra mobs. I use a warden build and managed to get a good RoW run, loads of healing pots and a ring of furor+8 with a glaive, wand of regrowth with camouflage to keep away from everything.