upon killing varian or garrosh, a top level engineer-rogue (engineer+pickpocket == safe cracker) in the raid would be able to loot the vault key. upon looting the key, a trap door or secret wall panel would open. going down the zig-zagging tunnel would lead the raid party to the city vault. the safe cracker would then start on the vault door. this could be a simple cast bar or have some puzzles that need to be solved (puzzles would be cooler as people are trying to figure out the answer in vent). once the vault door opens, it will pour out loot every 5 minutes for an hour (12 loot cycles) then slams shut for 24 hours. if all members of the raid are dead or beyond 50 yards from the vault door, it will close for 24 hours.
raise the alarm:
a faction wide alarm would go off once the vault door has been breached. this will bring players to the city to kill the raiders. (what? you thought it's supposed to be easy?)
every 5 minutes while the vault door is open, all living members of the raid within 50 yards will receive a 'loot notice'. this loot will come in 2 waves. the first wave is pure gold. the 2nd wave is 66% gold and 34% loot.
the 1st loot wave would be a random amount ( random( 40*500, 40*1000 )) that would be evenly distributed to raid members (if you only bring 20 members, you win big!).
the 2nd loot wave would be a lower amount of gold (random( 40*100, 40*250 )) and loot (13 pieces)
the 2nd wave of gold + loot (13 pieces) ... would come from the players of the faction being robbed. the loot would be from the banks of top level players* ... allowing them to respond. items selected could be anything from junk to epically rare soul-bound items.
*note: this spares lowbies from having their gold or items stolen while leveling
the fence is an exceptionally well connected group of goblins that deal in the shady underbelly of azeroth. there would be one outside of stormwind and another outside of orgrimmar in the cross realm zones. these locations would have a deep labyrinth beneath their unassuming shack. there should be guards (not too many), tellers, and maybe a goblin king.
keep in mind, the fence is in a cross-realm zone, so there would be plenty of enemy faction milling around should you decide to hit it
laundering is a delicate operation and takes time... about 1 week. during this time, the gold+loot is held in a storage locker at the fence.
for every round of loot awarded, raiders would receive a 'receipt' in their mailbox of the goods 'being laundered' at the fence... with a claim token attached (BOA). the token would be available to be claimed 1 week from issuance... and expires after 2 weeks.
upon a successful vault robbery, the victim would receive a note in their in-game mailbox. this note would come from the kings security and would detail their losses... along with a locker token(BOA). the token would indicate which locker their goods are held in, at the enemies fence. the token would expire 2 weeks from issue.
in the goblins labyrinth, there would be lots of chests and boxes. each would require a special key to open. there would only be 2 keys per chest... one held by the raider and the other by the victim. hovering over a chest would show its number (ie: chest A-1256) allowing for the player to quickly scan for the chest they need (they may have numerous chests to find). the chests they can open may sparkle to make it easier. upon opening, gold would be placed in the players pocket and items would be shipped to the players mailbox
we can't have the loot just laying around. any unclaimed loot will go immediately to auction on the black market auction house.
REQ mercs: http://us.battle.net/wow/en/forum/topic/7980249347
REQ assassins and bounty hunters: http://us.battle.net/wow/en/forum/topic/7980249354
if you would like to see this suggestion implemented, please paste a link to this thread into the 'submit suggestion' box in-game. i've been told those suggestions are delivered to development and it's one of the few ways they get input from players