This is a good quest to complete if you’re looking for a pass to cross the border to Novigrad.
The Witcher 3: Fake Papers
You’re going to need a pass to cross border posts into Novigrad, the second half of this map. This Shady Merchant found on the road north of the Hangmans Tree signpost (and just below the entrance to Novigrad) will sell you one for 100 crowns or he’ll give you one if you do him a favour and protect his brother-in-law as he cleans up the battlefield.
Wander over to the brother-in-law and clear up a few Ghouls, then talk to him to find out he needs help killing “corpse eaters”. This triggers the Bitter Harvest (suggested level 9) quest.
You basically need to kill a whole bunch of Ghouls and keep the workers alive. It’s not easy. If you fail you’ll stil get some crowns and EXP, but obviously more if you kill them all and keep the men alive.
When that’s complete, head back to the Shady Merchant. If his brother-in-law was killed you’ll fail the quest. If not, you get the pass.