Hmm.
Did you make a special suit? Perhaps you left energy resist alone, but refined all the rest down so you had 75 energy resist, but the rest of the caps were all low because you were running 65 DCI.
Combine 65 DC with HLA, and the UEV can't have more than a 10% chance to hit you - if you're with your disco swordsman, and you get the UEV's wrestling down to 110ish that might be even lower. I was going to figure out the exact numbers... but the Stratics page with the formula is not working. If each hit does ~15 damage (I'm assuming 75 energy resist, and that you're on an armored swamp dragon), and you on average will get hit once every 10 or so seconds. I also, shockingly, could not find the equations for calculating total hit point regenerated.
From memory: % hit = 50 + (differnce in weapon skills) + (my HCI - their DCI)/2. So from the perspective of a UEV, that's been disco'd down to 115 wrestle, and HLA'd: 50 + (115-120) + (-25 - 65)/2 = 0%, but we all know that every attack has a 5% chance to hit no matter what... so I guess you only need 55 DCI anyway...
Are you running energy eater at 30%? That would mean that on everage each hit will only effectively reduce your total HP by 10ish.
Or maybe you were in horriffic beast form as well as the above. With 24 total HPR, you're regening >2 HP/sec. Combine that with my "never get hit" suit idea + 30 energy eater and you could probably basically just stand toe to toe with no problem at all.
So... then you run a weapon with 100HML, 50 HLA, 50DI, Air Slayer ... 50 HLD?