How to get past "7-4"

Continuation of my guide describing how to reach the "7th world".
This guide is separated from the other one to avoid using images of that world in that guide.
This one will contain images from the 7th world, so beware of spoilers!

Introduction

• This guides asumes you know the steps on how to reach the 7th world, as they will be vaguely explained. If not, please, refer to this guide.
  
  
• I am aware that there is a guide that also shows all of the content inside here, in a more simplified and compact fashion, but it might be too overwhelming and confusing for newer players, so I tried to do a more comprehensive guide instead.
  Still, feel free to use the other one if you want. It's pretty good too!
  https://steamcommunity.com/sharedfiles/filedetails/?id=2255354338
  
  
• I'll also like to add an unprofessional thing to take in note, and that is that I'm not a native English speaker. Despite me being confident in my english, please, feel free to comment any grammar/typo you spot ;)

This guide assumes you know how to reach the 7th world already]. If not, please, head to this other guide.
https://steamcommunity.com/sharedfiles/filedetails/?id=2299525442
To be able to proceed past the "-4" mark, you'll need to do some extra steps on top of the ones that you need to reach the 7th world. Which at this point onwards, I will refer to properly say it's name, so if you don't want to be spoiled, this is your last warning.

1. Moon Challenge

The first step that we should add on top of the other ones, comes to place as soon as you reach the second world. You'll have to seek Tun, the npc that let's you enter the Moon Challenge, and accept the challenge.
You might be familiar with the challenge at this point, if not, all you have to do is dig until your pickaxe breaks, but since we have a goal in mind, we need to grab Hou Yi's Bow.
Once you have the bow, you can crush the pickaxe if you want, to instantly end the challenge, or you can dig for some money/crates. It's up to you! but as soon as you finish, be sure to keep the bow with you, as we'll have to babysit it for a while (basically, take it with us until 3-1).

• You can't miss this step, otherwise you WILL fail the run with the objective in mind. The only step you can "miss", is waddler's, if you are in co-op, or if for some reason you want to use a hired hand to take the bow for you.

2. Waddler (3-1)

Welcome to Olmec's Lair! in here, we have to use Waddler if we don't want to use 10 bombs to crack Kingu's shell, unless you have a hired hand or a co-op friend.

If this is your first time knowing about the existance of Waddler, he is an NPC that will carry things into deeper levels. Our friend will be located at the right of the entrance of the leve, at the top level, next to the ladder. You will need two bombs to open up an entrance to where he is.
(unrelated note: I'm using the same screenshots for the guide on how to reach the Sunken City, since I forgot to take some pics for Waddler, I hope you don't mind!)
Once you are inside, just leave your bow to him. You can also leave your back equipment if you press down and the button you use to enter a level.

• It doesn't matter if you have the arrow or not. We don't need to worry about any arrow until we reach the Sunken City.

You will retrieve the Item from waddler in 7-1, NOT in 5-1 (Ice Caves). Otherwise, you won't be able to hatch Qili

3. Waddler (7-1)

As soon as you enter the Sunken City, start looking for the back-layer entrance where Waddler is located. This time, the entrance won't be covered by any block. It will always spawn at 7-1, and in the odd-chance it is covered by a tile, try going to any backlayer you can find, and move your camera to try and spot Waddler's hideout.
Grab Hou Yi's Bow, and start looking for the Sun Challenge.

4. Sun Challenge

The Sun Challenge can appear at 7-1, 7-2, and sometimes even 7-3. This is probably the most difficult of them all, and the scariest too. basically, a stupid quantity of monsters will spawn in certain places, and you have to survive that. Not to mention, it's SO EXPENSIVE, so I hope you have 50k, otherwise you won't be able to proceed.
Necromancers, Sorcerers, Vampires, and more mobs will appear. You can try bombing a spawner (with paste, of course), then going to a safe spot, usually located at the top, depends on which spawner you bombed. Good luck.

Once you beat the challenge, all of the monsters will be killed, and you'll have to grab the Arrow of Light located at the center, and load it up onto your bow. If you try using a crossbow, it will break, without even firing the arrow, stunning you in the process.
Once you have everything, it is time to kill Hundun.

DO NOT ATTEMPT TO KILL THE HEADS WITH THE ARROW OF LIGHT, YOU'LL HAVE TO SAVE IT FOR WHEN HUNDUN IS DEAD

5. Bullseye!

All that is left, is to shoot the arrow towards Hundun's eye.
Congratulations! This is just the start of your new Journey.
Once you shoot the arrow, it will be made obvious where you need to go next. Good luck!