So here's what I've got so far (keep in mind that this is all sketchy at best, I'm lacking sleep and not thinking as clearly as I should be):
B/P team (not sure about the pet component yet)
1 R/Me with Greater Conflagration AND Winter
Say, umm, 3 R/Me with Barrage, LB Gaze, Mantra of Frost (fun fact is, we could even have all of them have Echo Gaze - yes, two elites, I know, very doable though, explanation later in the post)
What else? Yeah, 2 Monks, if possible with Healer's Boon (if they're healers) + HP, whatever else (don't play a monk) and Mantra of Frost. Not sure what would work for a prot, maybe Aegis or something.
One necro with Blood Ritual and Well of Power. Having something saccable would be a major plus, thinking about an expendable pet, perhaps.
Paragon with GftE, Stand Your Ground, Incoming! or Song of Restoration, Finale of Restoration, some spammable short-duration shout (Watch Yourself! on Tactics 0, even if it is useless).
Throw in a Ward Against Elements on someone if possible, lasting at least around 15 seconds, to match the recharge time.
Result = EVERYTHING is cold dmg. Nearly everyone except for one squishy has ~40% dmg reduction off of every attack + gain 2 energy off of it. That squishy can hit Armor of Earth and boom, around +50 armor; this is the squishy (probably a monk) with Ward Against Elements, which gives us another +24 armor against elemental. The speed decrease shouldn't matter, as nobody is actually supposed to be moving. Well of Power + Blood Rit keeps our little monk friends topped up topped up on energy, + gives everyone +5 health regen. If you're standing in the Well and the Ward, have Mantra up, the Rangers should have something like 124 armor + 40% dmg ignore. Healer's Boon + HP makes sure we'll all be alive and well almost indefinetly (considering that monks have a +2 energy regen from the Well and another +3 from Blood Rit, which the Necro can apply quite liberally under these conditions).
Correction: Stand Your Ground gives another +24 armor, so that makes it 148 armor for the frontline rangers for about 66% of the time spent fighting. GftE should be giving ~66% more chance of criticals, Finale of Restoration would be giving approximately 60 health each time a shout ends (which is every 5 seconds, if Watch Yourself is being spammed, plus whatever you get of GftE and SYG), Song of Restoration ~85 health every 15 seconds (this might be healing overkill, though, in which case using Incoming will negate almost 100% of the dmg when combined with Mantra of Frost, but Incoming has about a 15 second cooldown).
We can happily Barrage the crap outta them, use LB Gaze when recharged, if you want, one Ranger could even take Echo as an elite instead of Barrage and all the Ranger's take Arcane Mimicry. For all practical purposes, everyone can Echo their Gaze, and the one guy with Echo can Arcane Mimicry Barrage off of someone. Grab a Grip of Demonslaying if you can, have everyone be rank 3 or 4, you get a 40% increase in dmg done to the poor buggers.
End result = (with possible modifications) gg DoA (or at the very least the city area).
Discuss and improve, plz. (don't wet yourself, this hasn't been tested, but I'm quite sure it would work)
ALL THOSE INTERESTED IN HELPING TO TEST, CONTACT ME INGAME OR LEAVE A POST HERE. (sorry for the caps, I wanted that to attract attention ^^)
N

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) and everything was going fine until our dervish died.