Today I have flagged for ToD for the first time ever. I have located the cave. Entered on normal to look around. Won.
This was on a lvl 21 dwarven stalwart swashbuckler (second life, all ED though). I had most trouble in the second phase. I did not move at all. Cocoon and Sacred Ground and occasional CCW kept me alive (barely). Run out of my 700 spell points just when I killed him.
My resources consisted of: single deathward clickie. curse pots. few resist 30 pots after I realized I might actually pull it off. Selfcast buffs: blur, good hope. No DR breaker.
http://s9.postimg.org/gfffzyty7/Screen_Shot00000.jpg
Time 42 minutes. Including multiple breaks for reading the wiki and assisting daughter with plasticine. And lost 5 minutes after phase 2 wondering how to go up to the chest. I guess a prepared character could easily beat normal.