Mirror Cold Island

Mirror Cold Island is the 2nd Mirror Island. Like the other Mirror Islands, it holds a resemblance to its ethereal, that being the black haze of the Grumpyre If you look closely you can see the Wondermine from My Singing Monsters Dawn Of Fire All Monsters and Decorations from Cold Island can be placed on Mirror Cold Island. Basically, Mirror Cold Island is Cold Island with a slightly different appearance.

https://vignette.wikia.nocookie.net/mysingingmonsters/images/7/72/Mirror_Cold_Island_%28Icon%29.png/revision/latest?cb=20190420155530