In Blackpits, you'll meet a group of masters burning a house.
During the conversation, you will learn that inside hides a man they're looking for. If magister Reimond gave you his consent, you may take convince them that you'll take care of things here.
Use the hatch in the floor to enter the basement, talk to the man and convince him to leave his hideout. As soon as you're back with the magisters, you will be able to choose either side.
Choice 1: Help the man
If you decide to help the man, you will have to face the magisters. The biggest problem here is making sure the man survives. He has no armor at all, which makes him greatly susceptible to any kind of effect.
Reward: 26200 experience points
Choice 2: Help the Magisters
If you decide to help the Magisters, the man will have to be killed. It will be just a formality - he's virtually defenseless.
Reward: 19025 experience points