EDIT: I guess what i wrote before was a little messy and didn't explain it enough. So i'll do a step by step walkthrough.
STEP 1: Find a Invasion attack zone (Open world map and look for a skull icon)
STEP 2: Find a Necropolis in the sky
STEP 3: Look for a ball shooting out from the bottom point of the necropolis
STEP 4: Follow that ball to find the Invasion point. Notice alot of lvl69-70 undeads in the area and a purple summoning circle type of thing in the ground. And a big scrying crystal with about 3k hp
STEP 5: Farm lvl69-70 undead's. They all have a high chance to drop a rune (i would say 25-50%). When you kill undeads you hurt the crystal little by little (you have to kill a ton of these before it breaks). When it breaks 4 summoners will apeer and channel on the crystal. When you talk to them you can turn in 8 runes and they transform into a boss (around 100k hp and he can be stunned and slowed, probably other things too but that was all our group had) This boss drops one green scurgestone (you know the once you get if you have a argent dawn trinket on), about 75-80% chance to drop a epic item (only haste armor gear, NO weapon or trinkets). These can all be disenchanted. It's also a chance that a rare spawns among the undeads and he also drops an epic armor item (he has about 20k hp and hits like a *****).
STEP 6: Once done find next invasion point (should not be far away)
STEP 7: When you have cleared out all the invasion points in one zone you will get a message in the chat (someone is yelling something). Now there anit any more places in that zone. So find next zone that is under attack by looking for the skull icon on the world map
STEP 8: After farming for an hour or two you should have LOADS of runes. Now there is a vendor in Light's Hope you can turn those in for various rewards (a tabard that gives a achivment done, potions, trinkets and more). This vendor sells more epic armor haste gear. Shoulders and Gloves for all armor classes. They cost 15 runes (after 2 hours i had enough to by 21 shoulder). These epic items can be disenchanted too EVEN THOUGH THEY ARE BOUGHT FROM A VENDOR.
Since my party didn't know about this we all rolled for the runes. So even the people that couldn't disenchant ended up with 200-300 runes. If we who could disenchant took all the runes we would have ended up with about 2000 runes after 2hours. 2000/15 is alot of voids. And about 25-33% you get two voids from a disenchant.
EDIT: While i was writing this my server had a server restart so it might have been because of this to hotfix it (if it was something that was not intended on their part that is). My party has disbanded since it's 6:42 am here and non of us have slept so it's bedtime for me too. But maybe someone could confirm if it still works? If not i guess i'll find out tomorrow