So, have to agree with Vacant up top there. You are pretty all over the place here Evan. It's pretty hard to follow what you're asking for here. Our of curiosity (and don't take this the wrong way), but what is your native language? I just want to get a grasp on where you're coming from here. I understand that working in a language that isn't your native is pretty daunting, and my utmost respect goes out to all that do.
I'm going to give some general advice: When asking for help on a story like this, always reduce the information you're presenting to prospective helpers to the absolute bare essentials. We don't need to know all of the character names and the jargon. Break things down into concepts. Main character, side character, antagonist, primary antagonist, evil empire, father, best friend, the main character's weapon, the mc'guffin, etc. These are the kind of words that you should stick to. It makes it so that anyone can understand you without having to go into intensive research to learn your world first.
It's also going to be useful to you to think of things in these terms. Stories are made of building blocks. Think of them like legos, or your plastic toy brick of choice. Individual bricks are understandable to anyone who comes across them, but if you scribble unique names onto all of them first, it's going to be a lot harder to understand you when you say "the flat 4x4 piece attaches to the top of the 2x6 brick". But once you are also thinking of them in generic terms, you will have learned something fundamental about all stories. They're all unique once fully assembled, but broken down to their essentials, they are the same as every other one.
As to what Vacant said about the links: We ask that if you have stories, that you post them directly to the forum. No offense, but we don't really know you at all yet. Trust like that takes time to build. It's easier for everyone if you just post your stories directly if you want the help. That goes for posting things like the wiki you've built. It's cool that you've done that, don't get me wrong, but flat out, no one is going to take the time reading it to try and piece together your characters and world. A piece of writing should always stand by itself. Wikis are not there to help people understand your story. If a person can't understand the story from the 'published' material, then you have failed as a writer. It doesn't matter if you're the most accomplished author in the world or just another nameless kid on the internet with an idea. Plus, giving us the actual material in an easily accessible format will help us give you better information than any summary possibly could. Back to the lego metaphor above, the blocks will always be the same, it's how you put them together that matters.
Now, with that out of the way, let's get onto this arc of yours.
You definitely seem to have a bunch of ideas swarming around your head. I don't think what you need is for us to actually feed you specific scenarios. That's just going to lead to clutter. Clutter is the bane of the story writer my friend. You need to again, reduce things to their bare essentials. In this instance, ask the question: What is this sewer dungeon providing to the overall story? What purpose is served by your characters going through it? Who of those characters needs to benefit from having gone through the dungeon? Who does not need to be there? If that character doesn't need to be there, why do you have them there? Is that a good reason? What are the events of the story leading us here? Do they make sense logically? Is that reason contrived? Does the situation fit into the natural flow of the narrative? Is there an appropriately long rest from the action of the story before and after the dungeon? What do the characters ultimately hope to gain by entering the dungeon? (Not just the main cast, but every character we encounter). Does it make sense for those characters to be there? How are the events of this section of story going to impact the very end of the story? Is there any other way that those ends could be met? Would it be better if the results of this arc come from a different arc?
If you're having trouble answering any of the above questions, then you're trying to do too much. As the faithful acronym tells us: K.I.S.S., "Keep It Simple Stupid". Don't over complicate things that you don't have to. The reader will thank you for it.
Again, those aren't questions I'm asking you to answer here and now. They are questions I want you to ask yourself. They are also not an exhaustive list.
Now, some questions I do want you to answer:
- When in the story do the events of this dungeon/tournament take place? (A rough percentage of completion is fine)
- How many characters are involved? Grand total, and how many of that grand total are part of the main cast of character?
- In a single sentence, what is the result of this arc going to be? If you can't sum this entire thing up using a single sentence, then I can tell you just from that that you have over complicated the whole thing.
- What do you want your readers to feel during this arc? If you can, sum it up in a single word.
- Now tell me what makes that word different from the word you would chose for the arcs on either side of this one.
I hope that isn't too big of an ask. But we need to set a baseline here if you wan't meaningful help. You need to be simple and direct to get the most benefit from a topic like this. I can make up scenarios for your heroes to find themselves in all day, but if I do, then I have failed you, because I wouldn't have helped you better the foundation of your story. A strong foundation is everything Evan. If you take nothing else from this whole thing, I want it to be that.