Can anyone help on how to complete this quest, I couldn’t find it anywhere or is it still not doable?
You can complete the quest by finding and killing Archivist Thelon in Port Valbury.
For more info regarding this quest check the link below:
http://grimdawn.gamepedia.com/The_Outcast’s_Revenge
Yep, Quest is in Port Vocab…
Either in 2nd Area after the foundation, or the 3rd area the High Estates or whatever it’s called, is where I’ve seen him spawn…
Careful he’s a uber pain cause he drains your Energy 
Thx for the responses i found out this instance is located into the conflagration, intro the instance. Going to try and find the Head of Archivist in there, just crafted the skeleton key 
Activist Thelon is such a pain in the sphincter in more than one way.
Ive gone to Port Valburry Old town twice, I clear the whole map and I cant find Thelon. Is he in that Flame area, that locks when you enter? (it contains a corrupt chest). I make it past the first few waves in there, but eventually die.
Yes he is in old town, found him once at the south side. Took me one hour to finish that quest, had to clear the whole port, including the bosses. Aside from energy drain, he’s not much of an issue, but his companions however had too much damage reflection.
Thelon is some straight GARBAGE.
All his drain does is artificially, unnecessarily lengthen the fight with him to ridiculous proportions.
Lengthening the fight adds significant risk, because he might crit you more or something. The faster a fight is over, the less time there is for you to miss, him to crit, or you to make some silly mistake, or have your buffs/consumables run out.
Just add some energy leech resist, I think I have 30% or so from constellations, I just needed to use 1 energy potion for him
He’s just unusually tanky for a caster hero, and has temporary invulneranility, that’s all. His energy drain is annoying, but can be countered with spirit potions.
Just beat him on Normal mode, but now all I have is bounties.
After I turned in, not sure where the next quest is …any ideas?
No next quest, that’s the end of outcast quest line. But you should already reached revered state with outcast. I strongly advise against doing outcast bounties as they reduce your reputation with Black Legion, which is much harder to get