Just found the forum,
Just want to share a little about my time with Mega Boss:
Back in 4.x we can beat Dorudugan with any solo monk MS/SC without any equip/potion/scroll/summon in POTD. But this got nerfed in 5.0.
The main skill is Blade Turning + Dance of Death/Enduring Dance + Duality of Mortal Presence INT mode.
The support skill is Long Stride & Whisper of the Wind (WotW)
The optimum build should be SC monk INT/DEX Godlike that can reach almost 10 sec Blade Turning. If doing perfectly we wont received any damage with this build.
MC monk with high INT can achieve it as well (7-8 sec blade turning). Personally I found this method back then when using my Savanna Votary tank. The original build is similar with Kaylon's Herald tank but I use Iron Wheel + Bloody Links instead of Bardatto's + Magnera's Chain to proc Fighting Spirit & Blood Rage for Accuracy & Damage Bonus. And also Giftwrapper pet for extra armor & regen.
Blade Turning reflect his Basic and Disengagement attack to him, so we just need to move in and out around his 'engagement line'. This is generate very high in game time DPS: 100+ damage every disengagement reflect. With this method he only have opportunity to 5-6 Helfire Barrage before he down.
Brutal Cleave has surprisingly small area, if you move near his engagement line it won't hit us.
Helfire barrage can easily avoided with long stride and even easier if you votary like me with: stride + fast runner.
Magnetic Overdrive can be avoided with WotW invisibility for Monk SC or Survive it with precast Lay on Hands for my Votary, just don't forget to reapply the Enduring Dance after 3 hits.
For SC monk, you can finish him with Resonant Touch that come from WotW.
Back then, after success to use this method with my Votary, I save -> rush to new game -> create Death Godlike SC Monk -> and try the challenge, I only get hit twice with Brutal Cleave due to carelessness, but overall it possible to beat Dorudugan without any equip/potion/scroll/summon in POTD & without taking any damage (but require focus & concentration which is not my forte).
Just yesterday I found this forum and want to record the perfect run for this challenge and share it, but Blade Turning is already nerfed per update 5.0 so it will end after movement. It become impossible to reflect disengagement attack. But the real problem is to avoid Brutal Cleave we need to move, we still can move to the side to avoid Brutal Cleave but it will significantly harder and need to recast Blade Turning immediately . We still can disengage to avoid barrage with WotW. Overall the challenge is still possible but it will require tons more time & focus.
However if we cast aside the no Equip/Item/Summon challenge and only focus on how to melee tank Dorudugan, Blade Turning provide complete Resistance to Shield & Main Weapon Attack as well as extra damage from reflected attack, so all we need is decent reflexes & 14 Slash resistance for the Brutal Cleave + Rekvu's Cloak for Fire Damage which quite easy to get, and we are good even only with minor HP regen.
Actually in 4.x there's many other methods to face tank Dorudugan & still able to kill him, for example: Brilliant + Salvation of Time + Barring Death's Door.