I Know it looks bad. I'm just new to the whole wikia thing ^^
The Thieves Guild would have 4 "Levels" and 2 Special-class ones:
Tasks: Gather Cobblestone, Brown Mushroom, Melon etc.
Tasks: Battling in PvP arenas to get weapons and other materials aswell as gathering Potion supplies. .
Tasks: Make ingrediants for Potions like glistering melon aswell as fighting in PvP.
Tasks: Make Potions that will harm people like Potion of Posion, Potion of Harming etc.
This is where you will have to choose between two classes Watcher ( The Assasin/Spy class always standing being the life of the party and the good citizen ;) but ALWAYS having a bottle of poison hidden under the sleeve.) or Scorpion ( The Bounty hunter/Warrior class living in the sewers because they dont care who sees them kill) .
The Watcher Class (A)
Tasks: Make more complicated potions and helping the Guild Master with building shops and such. .
6a. Masquerader ( The ultimate spy always being one step ahead)
Tasks: Having reached the top the tasks are pretty much the same as before just that now you will have more power in the guilds decisions. .
The Scorpion Class (B)
Tasks: Fighting in PvP Arenas and do bounty hunter missions.
6b. Master Criminal
Tasks: Having reached the top the tasks are pretty much the same as before just that now you will have more power in the guilds decisions.
And then it would be the "Oracle" (one of a kind class) 7. The Guild Master
The entrance to the guild would be in a graveyard and the guild would be in the sewers (that i would build along with the graveyard if you like my idea ^^)