If you kill the clannfear and then use the open portal to go up to the top while the Daedroth has hit you with the the wildfire Damage Over Time effect, then that DoT persists indefinitely. It cannot be cleansed or purged. It does not expire or eventually go away. You eat 6K ticks in addition to what the boss throws at you and the automatic damage from the "Soul Churn" mechanic.
https://www.youtube.com/watch?v=lWYP8gWYvpA&feature=youtu.be
I have tried various methods of trying to avoid that DoT. I purged when I reached the top. I purged right before I used the portal. I tried to use the portal when the Daedroth wasn't breathing on me (difficult because that's its main attack, if he uses it before you kill clannfear, you still have DoT on you, and there is a delay between portal activation and actually teleporting to the top). I have managed to survive longer than the video I recorded. It does not go away. The Wildfire DoT was fairly consistent (for me) and the extra 6K damage ticks is something I cannot overcome (and believe me I tried).
A couple of things:
I have a friend who advised me to use the technique of ignoring the daedroth by nuking the clannfear and then using the portal. He has completed it multiple times and found it "weird" that I am experiencing these 6K damage ticks. This was not a fluke for me. I tried this dozens and dozens of times to notice something consistently wasn't quite right with the amount of damage you take up top. He either mitigates the damage entirely (unlikely, even though he is one of the best players in NA, he doesn't have indefinite resources) or he manages to get up there without that DoT. I asked him to pay closer attention to what happens once he uses the portal.
"Just kill the Daedroth." It is asking *a lot* to get thrown of the top and taking significant fall damage or flat out stunned in the lava and then having to immediately contend with the daedroth and the clannfear, both of which are instantly upon you (they track you from the bottom) and are hitting you for a combined 14K damage. I *can* do it ... maybe 40-50% of the time.
Edit: Now that I think about it, I believe
@usmcjdking is correct. That is, it may not be strictly a "bug." It does not mean I think having an unpurgable effect by a monster not even on the screen is a very enjoyable mechanic to overcome.
Edited by Joy_Division on November 18, 2015 8:51PM Make Rush of Agony "Monsters only." People should not be consecutively crowd controlled in a PvP setting. Period.