After meeting Dijkstra, Carlo “Cleaver” Varese, and Francis Bedlam at a bathhouse you’ll be ambushed by assassins and they will all agree that helping Geralt get to Whoreson is a good idea for everybody.
THE PEACEFUL PATH
You can completely disregard Cleaver’s offer to assist you in storming the Arena and the Casino but this is the more lengthy option and ultimately you will end up being ambushed and have to kill everybody no matter what.
Peaceful Casino Encounter - Casino
To get into the Casino without violence bribe the guards with 200 crowns or use Axii Delusion Level 3 on them.
1. DO NOT Mention Whoreson to anyone
2. DO NOT be a dick
3. Win 3 rounds of Gwent
If you do all these things you’ll be invited to a VIP game which is really just an ambush and you’ll have to kill everyone on your own.
Peaceful Casino Encounter - Arena
You are granted entry into the arena and can proceed to fight all 5 of the enemies they throw at you. Eventually Whoreson will make an appearance but Cleaver and his Dwarves interrupt everything and he orders them killed along with Geralt. So you end up having to kill a ton of his men anyway.
RESULT: When you get to Whoreson’s compound you can lie to the guards and say you have “fresh girls” for him allowing you to get in without combat and sneak into Whoreson's house through an alternate route. You will end up having to kill some of his gaurds after sneaking in.
THE UNPEACEFUL PATH
Choosing to team up with Cleaver and take out as many of Whoreson’s men as possible is quick and can help out with the inevitable confrontations you’ll encounter at the Casino and the Arena. Pursuing this path gives you the option to complete The Gangs of Novigrad quest and Honor Among Thieves Secondary Quest where you colect a reward from the King of Beggars after rescuing Dudu from the Casino
CAUTION: If you do not complete The Gangs of Novigrad before going to see Radovid with Roche then you will fail that quest line. Speak with Cleaver if you chose to raid the Casino and the Arena with his crew before going to Radovid with Roche.
After hearing what Whoreson has to say about Ciri you can decide if you want to kill him or not.
KILL WHORESON: Impacts your interactions with Dudu during Act 3's main quest Payback.
LET WHORESON LIVE: Meet Whoreson again during Act 3's main quest Payback and anger the other "Big Four" gangs of Novigrad.
After completing this quest and Count Reuven's Treasure the main quest The Plays the Thing becomes available. A Favor For Radovid is also available after this quest.