Seek the Saboteurs

This quest can be started hourly, when the Dark Iron Invasion pops up again at xx:30. You have to find Coren Direbrew in Blackrock Depths. This guy is a bit hard to find if you don't know where to start looking for him, so i made a little walkthrough.

First of all you got to have the Shadowforge Key, because you will need it for a few doors and a lever further along the way.
As soon as you come through the BRD portal take a left but don't go to the Dark Iron Highway. Instead turn right and open the small door, immedately taking a left to open another door.
In here there's a lever you need to pull for the bridge to lower up ahead.
Once you've clicked the lever head up the ramp and cross the now available bridge.
Work your way past a few groups of mobs at the other end of the bridge and you should pass General Angerforge. Head into the room adjacent to the general's room and then don't go straight ahead to Golem Lord Argelmach, but instead turn right past the room with the mechanicals and head through the passage there.
Once you're in the Grim Guzzer you should see Coren walking up and down the room, but as soon as you approach him he runs away into the nearby hall. He hides near the Thorium Brotherhood questgiver so that's where you can complete the quest and receive your Dark Iron Tankard, which gets you "completely smashed" instantly.

Hope this helps you guys find him too.

Well in case you haven't got the quest and know someone who has, but hasn't completed it yet, note that the quest is SHARABLE.
Good luck.

Edit: YES it IS sharable, check the Quick Info box, duh!
(Edited due to certain inappropriate comments below)

You cannot receive this quest as of now, until Blizzard reimplements the Dark Iron attacks.