Info about the levels:
The Fairy Glade: pretty basic, you dont need much information.
The Marshes Of Awakening: Alot of platform jumping, this place is full of mazes and is quite confusing.
Whale Bay: Quite hard, This has alot of jumping over orange stuff. (I think its lava, but I am not quite sure) The crabs can be hard to see, so watch out.
The Cave Of Bad Dreams: The first part is set inside the cave and full of hard platform jumping, there isnt much to say about it though. The second part you are in the outer section of the cave and you get to fly, and it is the longest stage in the game. The third part is still set in the outer section of the cave, and is full of sliding while dodging spikes.
The Canopy: This stage is full of climbing, and can be quite annoying and hard, so be careful.
The Sanctuary Of Stone And Fire: The first part is full of basic platforming, so it isnt very difficult. The second part has a music change and is full of sliding and dodging spikes, but it is EXTREMELY easy. The third part has you jumping from platform to platform to avoid rising lava.
The Echoing Caves: This is pretty basic and full of platforms, be careful, because some of the platforms are hard to see. (This stage has AWESOME music!

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The Precipice: The first two parts are very confusing, so keep your focus. The third part has some hard platforming, then you reach a boss, but it is quite simple, so I wont say how you defeat it.
The Sanctuary Of Rock And Lava: This place has very few checkpoints, so be careful not to die, otherwise you might have to start about half the level again.
The Tomb Of The Ancients: Pretty basic, even though its the final level, can be tricky though, the final boss is the same as the one in The Precipice.
Bonus World: I havent unlocked it, so I dont know about it.