Under New Management

This is the final quest in the Thieves Guild within Skyrim. The Dragonborn assumes the role and title of the Guild Master after completion. It requires all 'special' city quests from Delvin Mallory (not including Larceny Targets) as well as the entire chain of main quests to be completed. The 'special city influence quests' are offered by Delvin only after the five 'small jobs' have been completed in each city as follows: Riften, Whiterun, Markarth, Windhelm, and Solitude in order to restore the Thieves Guild's influence within that city and across all of Skyrim. Review the 'small jobs' and 'city influence quests' sections for details as well as Conditions and Tips.

Walkthrough
Once all side quests are complete, speak to Brynjolf who is wandering between the Ragged Flagon and the Cistern. Once found, follow him to the center of the Cistern where the Guild officers will initiate the Dragonborn as the new Guild Master. Once this is done, Brynjolf tells you to see Tonilia as she has something for you. Once this is done the quest will complete and the Achievement/Trophy, One with the Shadows, will be awarded.

The 'small jobs' from Vex or Delvin can still be carried out after completing this quest.

Rewards

 * Guild Master's Armor Set (increases pickpocket and lockpicking skills by 35%, 50 points carry capacity, as well as increase better prices with merchants by 20%)
 * Amulet of Articulation (persuasion attempts almost always succeed and speech skill is 5-35% better)
 * Key to the Guild's Tribute Chest (the chest located in front of the Guild Master's Desk in the Cistern contains random loot such as gems, coins, enchanted weapons, etc.)
 * Unlocks the achievement: One with the Shadows.

Achievements
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