Thread:Swtshani/@comment-22439-20130626201234/@comment-7326455-20130626233212

Gold Island is kind of like a bonus extra song you can make. Something to aim for once you've completed all of your other islands. As for why you can put monsters there from other islands, it's special. It's specifically mentioned in the description that it exists in another dimension - you're not actually moving your other monsters there, just... kinda copying them, I guess.