
Firstly, here are the skills (you'll notice that nothing has changed from the traditional method):
Monk
[card]Protective Spirit[/card][card]Healing Breeze[/card][card]Spell Breaker[/card][card]Bonetti's Defense[/card][card]Blessed Signet[/card][card]Blessed Aura[/card][card]Balthazar's Spirit[/card][card]Mending[/card]
Template Code : OwEV0SX8SIXnoegMi8NlAUeiEA
Necro
[card]Arcane Echo[/card][card]Spiteful Spirit[/card][card]Ancestor's Visage[/card][card]Sympathetic Visage[/card][card]Desecrate Enchantments[/card][card]Reckless Haste[/card][card]Blood Ritual[/card][card]Resurrection Signet[/card]
Template Code : OAVEEKZmd8sEyDiAPoLUo9GEAA
Videos:
Monk Perspective:
http://files.filefront.com/WAX_UW_Mo.../fileinfo.html
This video shows off the monk tanking 5 Aatxes, while the necro manages the scatter. One Aatxes breaks and starts attacking the necro
Necro Perspective:
http://files.filefront.com/WAX_UW_SS.../fileinfo.html
This video shows the monk tanking 2 Aatxes and 3 Grasps, the necro moves in and ends up taking most of the aggro at the end of the fight due to severe scatter
http://files.filefront.com/WAX_UW_SS.../fileinfo.html
Another necro perspective of the monk tanking 5 smites, scatter occurs and an ecto drops

http://files.filefront.com/WAX_UW_SS.../fileinfo.html
4 Aatxes aggro'd, the necro manages the scatter of one of them. Notice the bleeding at the end
The Difference
The difference in the build is this: The necro runs as a 55 necro
Yes, a 55 necro. Obviously you will need the -50hp CoA Cesta, and I suggest using the Curses Wailing Wand you can craft at Vasburg Armory in Cantha as your primary, and bringing along a StoneReaper if you need some extra energy for a quick cast.
Understanding scatter
In hardmode, when you have a mob of more than 3 monsters, and AoE damage is applied to the mob, the monsters will scatter to try and heal themselves. It is this scatter effect that makes duo'ing difficult and often results in the poor necro getting obliterated.
If we look deeper however, we might wonder WHY does the necro get killed during scatter, and the answer is simple - while scattering, monsters can still obtain aggro of a different target and their initial intention of healing themselves is superceded by their desire to kill anything they can.
Now that we have this basic understanding of what is happening, lets look at how we can 'harness the scatter'.
Harnessing Scatter
I will assume that most teams do not aggro more than 3 aatxes at a time, so I will discuss how to manage smite scatter instead, since this is where most teams fall over and /resign.
Assume that you have just entered the Ice Wastelands and are facing a group of 5 smites. You know that after the initial SS, 2-3 of the smites will scatter to heal, making the process of killing them exponentially long (if the necro doesn't die). However, with this method, we WANT the smites to scatter and aggro onto the necro.
Here is the method we use - we are in no way saying this is the only way of doing it, but it is something we've been using since the nightfall nerf of SS, and it works like clockwork.
1. Monk obtains aggro of the group of 5 smites
2. Once the smites have settled, the necro runs into the monks aggro bubble
3. The monk will signal to the necro that he is stable and ready by casting PS and HB on the necro. Due to the recharge times of PS and HB, the monk can now start cycling the casts of these spells on himself and on the necro. Do not miss a beat here, else one of you will die.
4. Once the necro has the protective spells on, he can cast his SV and AV.
5. Before casting SS, the necro must run directly up to the monk (i.e. stand next to the monk putting himself directly in the firing line of a rogue smite).
6. The necro casts SS on the smites.
From here things basically take care of themselves. As expected, a second or so after the intial SS is cast, a few of the smites will begin to scatter. However, because the necro is in their immediate aggro area, they will immediately aggro onto him, and come back into the are of effect of Spiteful Spirit, hence continuing the damage in an almost seamless fashion.
As long as the monk and SS do not move and just continue casting the necessary spells, the smites will not scatter again, and will die just as they usually do.
It is very important to understand that moving will potentially break scatter and will mean that the monk and SS have to start all over again on the mob.
[EDIT] - The max mob size you can aggro is 6. For some reason, if you have 7+ monsters aggro'd, scatter will occur, and not all the monsters will aggro onto the necro. No idea why this is this way - just an FYI

Where else will this work?
Well, the truth is, it works everywhere. All monster types. So yes, you can aggro a group of 2 aatxe and 3 graspings in the chamber and destroy them as easily in HM as you can in Normal Mode. The only provision is that the necro needs to be aware of monsters that can interrupt the monk. If the team faces a mob of these, I would advise that the necro maintains SV and AV on the monk in order to minimize interrupts while the monk is keeping the team alive.
Variations
At this point, I don't know of any proven variations of this build. Due to necro needing the same life maintaining spells to be cast as the monk does, we find that PS and HB are the best for this purpose. I would be very interested to hear if anyone comes up with new variations tho

General Notes
Firstly, thanks to my friends who helped perfect the build and method (Martin Pwns UW [WAX], Blue Serena [WAX], Skyspirit Necro [WAX]).
With regards to run speed, it is only a little bit slower as compared to a normal mode run, and you gain the benefit of higher gold drop rates (ecto rates don't seem to have changed) and obviously much more XP.