Wow the big man himself is giving us quests now. He's not quite as cool in person as when he was a mysterious symbol. Anyways with each quest he hints at a master plan, a final heist that needs a lot of magical items what could he be up to? Now that you're talking to the boss himself he'll let you ignore one of the tenets, namely killing someone while on the job. The quests from here on out can rarely be pulled off without any fighting and they're also longer dungeon crawls. There are some vampires so take a cure disease potion before bed.
Turning a Blind Eye
You need to have fenced 600 golds worth of goods to begin this quest. In the Imperial City there is an elf named Methredel who carries a message, telling you to travel to Bruma. The Gray Fox aks you to steal Sevillas Stone for him from the Temple of the Ancestor Moths. The Temple is north of Cheydinhal and marked on the map by the Gray Fox. The stone is hidden in the crypt, full of blind priests, traps and maze-like corridors. The priests are blind, but have very good hearing and will attack you. There is a blood price to pay if you kill any innocents. A good sercurity and sneaking is almost esseintial. The stone is in the end chamber and nets a 500 gold reward for returning it to the Gray Fox.
Arrow of Extrication
Boots of Springheel Jak
The Ultimate Heist
Aftermath
So now you've completed all of the Thieves' Guild quests what do you do now? Well you could just keep on stealing. All guild requirements are now gone, but you can continue adding to your guild tab by selling to your fences.
Guild Headquarters
During the finale of the Ultimate Heist the Gray Fox gave you the guildmaster's key. Head back to where you first met Armand Christophe all those levels ago and unlock the door. Inside you'll find almost all the Imperial City thieves' hanging out and chatting. There are a could of bed mats if you need some rest and a small room with lockpicks on the table.
Head upstairs and you'll find yourself in a fairly nice house. It's got plenty of books and tableware if you want some and a door to the street that doesn't open. Head upstairs again and you'll meet Armand standing outside the door to your room almost 24/7 (this is ideal for paying off bounties you may have racket up in the Imperial City. Head into your room and see a nice bedroom only for you with a comfy bed and some nice items around the room. There's even a wanted posted of the Gray Fox for you to laugh at.
One of the most useful things about the guild headquarters is that only thieves' may enter. No matter how many guards are chasing you when you enter that door you're safe and you can head upstairs and pay off your bounty to Armand.
Being the Gray Fox
Now that you've got the Mask of the Gray Fox you can become him at will. It's a sweet mask that is ideal for thieves. It has detect life (120 feet!) so you always know where the guards are, Feather 200 so you can carry tons more loot, and stealth +25 to make sure you don't get caught. Overall it's the ultimate headgear for a thief.
It naturally comes at a cost though. When donning the mask you become the Gray Fox and thus you're guilty of all his crimes. Guards will swarm to you if you enter a town with it on and give you no choice but to resist arrest. Of course this can be easily avoided, simply take of the mask before they get to you or if you can't get it off that fast simply take it off and yield to the guard. It's endlessly entertaining watching guards rush towards you with the mask on then greet you pleasantly when you take it off.