MDT set has always worked on avatar nuking for me /shrug and I killed Ogopogo 2 days ago, still functions the same
I been working on my souls decently lately and I been fighting Brulo because I needed pup/bst seals. I tried fire resist atma's and still got hit for 3500+ on his Inferno. and his FireIV hit's hard w/o PDT set. Idk to each his own. Just my two cents, I hope this helps.
Very high chance fire resist wouldn't do anything, all avatar 2 hour abilities have extreme accuracy even if you used 2 fire resist atma and barfira with fire resist gear
However you can lower that to a guarenteed ~1700 with capped MDT + MDB gear, barfira, without using Magic defense atma and without having to play the odds hoping for resists