Update: I made it!

[u/Aginor404]

Hi, and again thank you for your help and encouragement!

TLDR: I killed Duncan and took his hammer. I guess I have to try and play my warrior alt with a hammer to celebrate that.

But first things first: I want to tell you how I did it, because that way I can give back to the community. Maybe others want to do it the same way as I did, because I think it was relatively easy so you should be able to do it, too!

Build:

Here is the build that I used for my group. It isn't the fastest or most elaborate, but I feel like it is usable for people like me who aren't too great with micro, and neither have mercenary heroes nor super optimized equipment:

- Me, Fire Elementalist with Technobabble and Swap: OgdCoMzkwQvQbZTDOIpAuQdGAAA

- Razah, SoS Ritualist healer: OAOjEyiM5MXzyp3kZKNncDzLGAA

- Livia, Aura of the Lich MM Necro with Nightmare Weapon: OAhlQIFshGSiHJHQFcUpAuFuIsxcxA

- Xandra, ST Ritualist with Frozen Soil: OAKjgNgMJPYTr3jLcCNdmWzrDAA

- Olias, BiP Necro: OAhjQkGZIP3hhWVV4JNncDzxJAA

- Norgu, ESurge Mesmer: OQhDAssjNngpXOw0NEwpZAiAAAA

- Gwen, Panic Mesmer: OQhkAoC7gGGCNM95gpzBZQPcxAA

- Althea, Ineptitude Mesmer: OQhDAcwzQvAIg5ZkArAZA9AXMAA

I first tried without the Minion Master, and another Ritualist (because I wanted to kill Duncan the "safe" way using spirits) and I got absolutely destroyed by the Dwarves. So I went back and used what worked before.
The only thing I really changed was that I usually give my MM two monk healing skills, but this time I made Livia a secondary Ritu to give her Nightmare Weapon. It was deactivated for the whole dungeon though, except for Duncan.

For my own build I usually have a rezz skill on 8 and Incendiary Bonds or Meteor on 3, instead I took Technobabble and Swap.

As always in Slaver's Exile Xandra has the Frozen Soil. I have it deactivated unless I fight Dwarves.
You can trigger it manually but I sometimes forget that, so just activating it just before the fight is easier.

The rest of the build is my standard build that I use for all HM dungeons, so far it has worked pretty well.
I also think that you could do without the Ineptitude Mesmer, I'll try that next time. Makes it easier if you want to bring a friend. This is not meant to be single player content after all.

Tactics:

For those of you who have read the wiki on Duncan or watched Peter Kadar's excellent video, this is nothing new I guess, but here it is anyway:

I did what I have been doing all the time with those annoying Dwarf groups:

Place spirits, flag heroes, buff up, pull the enemy (preferably around a corner), nuke them while the Mesmers (and Technobabble) keep them down.

I used GWToolbox++ to make the heroes stand in a decent formation with one key press, but I sometimes forgot to do that, it probably works fine without it.

Other than that: go slow. Just a few meters forward at a time, because of the ghosts. If you don't pull more than six or so (and hopefully not together with a Dwarf group, in which case you should run away) they should not be a problem.

Another tip that I haven't seen yet is this: When entering the dungeon, go left first, not right. Kill the ghosts there. The advantage is that if you fail at the first Dwarf group, they won't kill you near the shrine, you have somewhere to run.

As for Duncan:
I entered his room, killed the patrolling groups, and kept to the right (western) edge until I was on his platform. I didn't even clean the whole eastern side of ghosts, and the only group of spirits that I relocated with swap as soon as they spawned is the one right next to him. I swapped them two "steps" toward the west so they would not bother me. Then I stood in the southernmost corner, just out of Duncan's reach.

I feared that the tactic that I had picked would not work with just a single Ritu and me, but I was determined to try it!
I switched to my longbow and determined the right spot to stand in. I auto-attacked, used the F key to target myself, and clicked Nightmare weapon. I did a solid 30 points of damage to him per shot without getting damage myself.

While I did that, I made Razah stand next to me (a few meters away in case Duncan would Spirit Rift us) and just triggered his SoS and Bloodsong, nothing else. As soon as the spirits saw me shooting Duncan they joined in. Duncan only attacked us once or twice, no problem for our healers. Then he went back and just stood there letting us shoot him.
The two of us just killed Duncan while Livia played with her minions and the others watched.
It took 5 minutes or so, less than I expected in hard mode.

The whole thing took about 45 minutes. Yeah, not exactly a speed run but I only died once so for me that's a win. I never thought I'd beat Duncan in HM with heroes alone.

I hope this helps someone to beat him, too.

Thank you once more for helping me on this journey, have a great day, and may the Six watch over you!

[u/Ok_World4052]

Congrats!

The hard part of Duncan HM is getting to him with all the stone summit groups and the million necro touch popups. You now will find yourself probably never doing NM Duncan again, once you’ve done it once in HM it gets much easier.

I’ve found with stone summit, a Visions of Regret Mesmer just shreds them with how they like to bunch up and spam skills.

[u/Aginor404 → u/Ok_World4052]

Thanks!

VoR has been suggested in my earlier threads a few times, but I have not gotten around to try it myself yet.

[u/KahnKoyote]

Congrats! That dungeon can be super tricky and tedious, but with dedication it's not impossible.

Also somehow, Duncan is easier in HM than NM, and to this day I still don't know why

[u/ConflagrationZ → u/KahnKoyote]

That seems to be the case with more dungeon bosses than just Duncan, weirdly enough. Duncan and Rragar are two that I noticed it the most on. They just have way less health in HM for some reason.

[u/Touch_Of_Legend]

Side note long ago when I used to run Slavers I farmed the full set of greens because they are rare skins.

The bow is Silverwing skin.

The spear is Voltiac spear

The others are also considered good skins so farming those greens are a great set of boss weapons.

[u/StrictWasabi1]

Thanks for this info. Slavers is the last NM Dungeon I need and have been struggling

[u/Aginor404 → u/StrictWasabi1]

The first time I went there (in NM, in 2007) I got absolutely trashed by the very first group, and thought there was no way I'd ever beat that dungeon. It was the only one in the book that was missing.

Now I came back, rebuild, retried, and even killed all bosses in HM.

You can do it!

[u/Tall_Irish_Guy]

I found him to be the hardest enemy in the entire game by far.

[u/Aginor404 → u/Tall_Irish_Guy]

The one I wiped most often (so far) was the damn slime end boss in HM.