The Castle in the Sky mod adds a secret castle hidden away that you’ll need to establish a master level in trading with a village cartographer first in order to find it. This can take a while if you haven’t already made a reputation with a village but eventually you’ll be able to trade up to what you need.
Once you achieve that master level then you can trade with them for a Levitation Stone. This stone will give you a path to the location of the castle once you right click to activate it. It will immediately show you the path to take with a very long trail of clouds that’s only visible while holding the levitation stone.
And now you’ll simply need to follow the trail as long as it takes to the glorious castle in the sky! But be aware that the castle could very likely be tens of thousand of blocks away so bring all necessary items you’ll need along the way. This trek is very much a part of the fun of this mod since it forces you to travel much farther than you likely have in this world.
The castle is pretty hard to miss as it is incredibly massive but it’s also very high up in the sky. You can work your way up there by any way you see fit but you can also use the levitation stone to float up there as well. And once you reach the castle, you’ll now need to conquer it by solving a series of puzzles and defeating mobs in various dungeons. Also you won’t be able to break or place blocks until you conquer it.
There are chests hidden all over the castle with very valuable treasures and items, some of which you’ll very much need in order to conquer this castle. Some are in plain sight and others are hidden or locked behind redstone puzzles.
The puzzles can get very complicated but you should be able to figure things out as you go. You’ll need to obtain yellow, red, and blue keys to unlock the doors of the same colors to advance further into the castle and dungeons. You can get these keys by finding them in chests or simply killing mobs. And you’ll need many of the keys so try and stock up as much as you can before delving too deep.
You’ll likely notice how many mobs are crawling all over this castle simply by how many of them you’ll hear through the walls, which can be very daunting but if you’re well equipped then you should be able to handle things just fine. You’ll also find several elytras in these chests which can come in handy if you fall down a deep hole and need to get back up to start over.
Then just find the corresponding doors until you reach the room with the Levitation Crystal. This is where conquering the castle comes into play and all your hard work will have paid off. You just need to flip the lever next to the crystal.
After turning the lever next to it you’ll now be able to break and place blocks! You may spend several hours in the caste but that’s what makes this mod that much more entertaining. It adds a significant amount of adventure playability simply by making the trek all the way to finding it and then the level of difficulty in trying to solve and conquer it. This mod makes for a great multiplayer server since you may benefit by having multiple people helping to solve the puzzles. Plus with all the valuable loot you’ll find, there will be plenty to go around and share amongst the team!