Then and Now, Here and There - How to beat Dahgar the Eye of Flame?

I played about halfway through Prophecies and almost finished Eye of the North with only the help of henchman and heroes. Didn't have too much problems so far.
But now I wanted to do "Then and Now, Here and There" and it's like I'm suddenly running against a wall. It's just ultra difficult all of the sudden.

The first part of the quest took me like 15 tries because often I'd had at least a 30% death penalty before even arriving at the target and then being unable to continue because I couldn't even beat the last few enemies anymore.
Now I crawled up all the way to Dahgar and I just can't see how I could possibly do that. The best I managed was getting him down to 50% health.

The party can only consist of 4 people.
Gwen and I obviously need to be in there. The other 2 being Ogden and Mox (Vekk being the only other one available to me).
Henchman are no option because they are Level 4 there.

I'm an Elementalist/Necromancer Level 20. Tried to go all out damage with Fire, tried freezing and blinding, tried to put everything in Bone Horrors.
Just nothing works.
He goes after Ogden. Mowing him down with 3 strikes. He gets resurrected and owned again a few seconds later and after that it's just a matter of seconds till Mox and Gwen follow.
And after one failed attempt I can start over again as there's no point facing him with even 1% penalty.

Tried 11 times so far.

what are your skills?
what set up are you using for gwen, ogden and mox?

(I used gwen as an sos, I also used an mm and a healer.)

If you've almost finished EoTN, you should have a lot more heroes than that.

Jora, Livia, Xandra, Khamu, Pyre, Anton, and Haydra. Most of these are irrelevant for you case, except for Livia and Xandra. (Hero rangers are useless outside of being assassins, and you already have MOX if you needed melee. And paragons are.. well paragons).

You have a couple options. The most tedious one is, you can caravan down from Yak's Bend and take 6 with you instead of 4. You really don't need it though.

Technically, all you need for that encounter (as is true about almost all PvE encoutners in EoTN) is Pain Inverter and a healer. Having a minion/prot is also handy.

I would suggest a party of you, Gwen, Livia, and Xandra. Use the Illusion Mesmer build for Gwen and The Minion Prot build for Livia from here: ( http://www.gwpvx.com/Build:Team_-_7_Hero_Player_Support ). Swap Death Nova for Signet of Lost Souls on Livia (this reduces her dawdling around 'buffing' her minions while you're running into the next combat).

Turn Xandra into a healer. Ideally, it's nicer to have another necro be your resto healer (as soul reaping from all the dying minions keeps their mana up), but you're stuck with 1 necro at this point. If you can go unlock Olias, I would do that.

For you, it really doesn't matter what you bring beyond Pain Inverter. If you don't want to do it, then you can generally get by with a SF build ( http://www.gwpvx.com/Build:E/any_Sea...s_Elementalist ). bulking up the enemies on corners help a lot. Otherwise, you can probably do better by just brining domination skills. As a human, your ability to interrupt the more important things are handy. Otherwise, you can't really go wrong with a spirit spammer build. If you can swing it (not sure what campaigns you have)

I don't find hero monks make very good healers. Their AI really isn't conducive to the intelligence to make the monk healer to work well. Spamming Mend Body and Soul is about at their limit.

Also, try to split the groups up by pulling with a longbow/flatbow. Flag your heros in the back around the corner, tag the nearest person, and walk backwards as they run towards you, this helps to bulk them up too.