1) Start with the get Junior Quest, until you have all the options free how to continue further
2) Go first to the Hideout at the Temple Area, as theres no fighting, just search with Witcher Senses everything up, until you discovered all red things, just to realize, that here are no clues about Junir, nor Ciri and to get this obsolete task directly done and of from your to do list.
3) Go now for the Casino, without having talked with Cleaver, so that you can do it solo, don't talk with any of the NPCs about Junior/the owner, or the Card players become suspicious of you, if you belong even into this place, or even warn you, that they call the thugs, if you keep on asking about Junior so directly ect..
Instead, play and win best 2 Gwent Matches, then instantly accept the offer to the obvious trap to kill in a hidden place the minimum amount of 3 npcs without that you have to fight everyone, this ensures as i learned now from this thread, that the Secret Passage stays open, as we seem not to kill the 2 friends of the gate guards then, which must be the 2 door guards at the front dooor of the casino, so they aren't later hostile and explain you ,where the secret entrance is..
Be caustion, the battle up there is tough in DM difficulty, as the room is very small and not really good for a fight there agaisnt multiple opponnents that hit like trucks, if they can quiickly hit you together from behind, as one uses also an axe that does significant damage, if the wielder hits you from behind with it and staggers you, making it possible for the other 2 to finish you quickly off when you get surrounded. So be prepared to make maybe some reloads here if you die.
At the end, free the gnome to get a little reward sidequest.
4) Talk now with Cleaver to get his raid for the left over Arena running. Quest Log doesn't mention anymore Casino, if you have it done already the Solo Way, before talking to Cleaver
5) Now you have to do only the Arena with the help of the Dwaves, be careful, the arena is full of lvl 12 enemies that easily can kill the dwarves with like 1-2 hits and you don't want them all to die, or Gangs of Novigrad will instantly completely fail!!!. SO work alot with Axii and Igni and use strong defense ignoring attacks against Axe wielder, quickly take out shield wielders with Axii and make your foes burn if needed with igni to prevent them from attackign the dwarves as burnign enemies stop attacking and make it naturally also for the dwarves easier to kill for you the NPCs. Try always if possible to attack enemies from behind, as you will do signicantly more damage then.
You can try to kill more npcs of the following rooms, because not always do rush all the survived dwarves quickly to the next room, it can happen that they stay behind a safe iron grit door, as long as 1 thug is still..but make sure you use here potions/Decoctions, as they make all the battles significantly easier. A sword that has a good chance to burn/freeze foes is also very helpful here or one with very high chance for critical hits and naturally the oil that increases damage agaisnt humans, as high as you can get it. Quen is also your natural friend here, use it to protect the dwarves as good as you can, by taking rather self the hits playing kinmd of bodyguard here as you absolutely want, that at least 1 single dwarf survives all this mess. Make best a save file before doing this in case that you fail to protect the dwarves and all die.
6) After having killed of everyone, DON'T FORGET TO LOOT IGOR FOR HIS KEY, as only when you loot it, you can open his little box to get the Info about the existance of a Secret Stash that is in the very near, halfway in a sideway, that leads you a stock deeper to a place, where when you use Witcher Senses will see a red marked torch and a yellow place at the wall which is the Secret Stach, use the Torch while holding the Witcher Senses to interact with it, voila, loot the Stash.
7) Return to Cleaver to fiinish Gangs of Novigrad. Due to the point, that you have doen half of the work without his help, he will give you also only half the reward (150 gold instead of 300), but Gangs of Novigrad will be finished with no fail marks and stays also so, its basically fixed to this point..
Always make sure, that you finish Cleaver, before finishing Count Reuvens Treasure Quest
8.) While being at the Reuven Treasure Quest, ask Menge first for the Treasure, then Dandelion, if you want to get a better rewards later at the game, even it it might be useless, but also a large amount of Gold, even if also that you won't need anymore, as its way too easy to make tons of gold early on and at the point of beign at this quest, I had already over 20000 Gold+) If you don'tcare about Dijkstra being happy, ask about Dandelion firts and you can watch a beautiful and yet so awesome angry Triss finish off Menge for the tortures in her charismatic blind rage. (really love Triss in my German localized game, the actress made such an super awesome job, exept for the torture moans, but I guess, too realistic and USK wouldnt have let the game through as being for mature players as i know this crap rating institution of our country...)
If you killed Menge, before the torture has ended, you have to do a little Side Task more, meeting up a Spy at Ferneck called Yarmak or something similar. Quite entertaining too as a little alternative for not seeign the cruel awesome Triss earlier
9) After having done first Cleaver with Solo Casino before talking to him, Dwarf Raid Arena after talking to Cleaver, Looting the Secret Stash and finishing Cleavers Quest, before talking with Vernon/Radovid, then has the tiem come to finish the Get junior Quest.
10) Due to havign done Casino Solo and not having killed the Casino Guards, the Juniors Hideout Guards should be now friendly towards you, when you say to them, that you are the first time here, and that you come for the whores, then they should tell you about the secret Entrance (at least thats what I read about it in the Internet), then use the Secret Passage that you find in Oxenfurt in a house south east of it near the water. if you cant find it, just google Witcher 3 Secret passage and you should find a video about it, which shows its location on the minimap on second 5.
11) Use the Secret Passage, loot the Schematic for the Enhanced Catt School Trousers, if you weren't here before, kill off some junior thugs and kill Junior at the end to finish Get Junior and when everythign of this has been done right and CDPR are not antisocial trolls that like to punish perfectionists, then this should solve this quest mess with finally having both quests done with no fail mark and no failed gang of novigrad quest!!
Junior wi ldie so or so, so no reason to spare him, and it feels so much more satisfying to kill this dirty bastard self when Geralt is already in a serious bad mood anyways ^^
I'll make a final 3rd and last big try for this thing here, to test it out, if this theory gets it finally done right. my last try I made arena solo and went into casino with dwarves, just to see, that arena gets killed off everybody at the end anyway, so I thought, this will be for the other way around also too the case with the Casino, that everybody will get killed anyways.
But after reading this thread, I never thought about it before, that taking instantly the choice to go into the trap might turn out, that not everybody gets killed there, including the 2 door guards!!, but just only the 3 npcs in the upper stock behind the closed door where nobody of the other thugs recognizes the rumble up there, so that you could leave the place without that everyone got killed.
