How come? I've beaten that with a mage and rogue. With mage I had stone golem to tank for me, on rogue I was just debuffing him with mark of imperfcetion (name could be wrong) and avengers auto turret. I don't remember my exact toughness for these toons but my mage's stats were 7 ferocity 2 agi 1 toughness, rouge= 6 agi 2 toughness 2 ferocity. Only problem I had was about the ring of fire skill of the boss, you have to dive into it using dodge (SPACE KEY DEFAULT) so use your stamina carefully.

If you are melee, i have no suggestion since i've never tried since i dislike skill visuals of melee skills.

Overall tips:
-Either have a pet tank the boss while you deal damage or have something (minion/turret) to deal damage while you avoid getting hit.
-Spare your stamina, use wisely
-Have at least one movement skill in skillslot and always maintain enough resources for emergency use of movement skill
-Use debuff and/or ailment DoTs on boss to melt him quickly.
-Focus on staying alive rather than killing him, stay calm.

-> How come? I've beaten that with a mage and rogue. <-

U must be the real hero then.
The game balance on this boss is just not fair. Game Breaking.

On my first character I could not beat him. I was stupid enough to think I could make a melee Poison spamming assassin. I got my ass whooped so hard. So I grabbed a staff. Got the spell Ice Shard, a Golem.. And I literally spammed from the corner of my screen while I kept resummoning the golem as he died.

Was it fun? Absolutely not. But melee is just a waste of time.

In act 2, I found out Bleeding edge is OP as fk. And so is bladestorm. I completely respecced to Rage regen. Rage gain on kills and default regen instead of willpower. I can tell you. It goes from incredible underpowered as melee, to freaking godmode piss easy. And after finishing the story mode, I found out bleeding edge has another OP passive in that breaks the complete game lol.

Theres not a lot of room for trying builds. It either works or it doesn't. You cant just pull through with a medeocre build if you ask me. The dmg output of enemies is just way to high. And currently im a 100% in toughnes loool. Still get 2 shot sometimes.