Bowser Jr is defeated for the final time in his Boomsday machine to get the 5th grand star to open up world 6
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https://www.youtube.com/watch?v=tKLYj9v9Ciw
Going through the Forest temple rescuing monkeys who help you get to different areas in the temple, the mini boss is a big monkey with a boomerang, once beaten the boomerang is earned and used to get through the rest of the temple and defeat the Twilit Parasite Diababa boss battle with help from the big monkey and bombs, the first Fused shadow is aquired, the forest spring light spirit tells Link to head west where he will find his friends and the light spirit called Eldin but these lands are also covered in twilight, if entered Link will turn bad into a wolf and Link must also rid it of twilight
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https://www.youtube.com/watch?v=wGQPPvhln58