2 Affliction Warlocks, both tailoring and both sacrificing everything for +shadow dmg pre-TBC and good old fashion +dmg once they go through the portal.

With a bit of practice, they could just chain pull mobs without ever having any downtime (not even bandaging). With good +dmg a Warlock can pretty much kill a mob with his 4 DoTs (3 DoTs pre-UA, obviously), 2 Warlocks would mean a mob would be unlikely to reach them before it died to DoTs especially if it's a runner. The only real problem would be finding a camp that respawns fast enough if the duo decides to grind instead of quest.

1-29: http://www.wowhead.com/?talent=NVZ0xIzh (improved Voidwalker maxed at 17 and then Corruption and back to demo)

30-70: Respec into http://www.wowhead.com/?talent=IEMriRfkqtboMxc0c (only 2-3 points in Suppression early, only max Emp. Corruption post 60, Nightfall is filler for leveling).


Plus it's well known that 2 Affliction Warlocks zoning into an instance causes all the mobs to fall over dead.