For a new Biome islands I have 3 ideas for ones ender valley is a long valley filled with a grey ender men ender golems which are nultul ender cows which drops al sorts of meat including fish and last ender villagers which live in ender villages and trade for end powder.

Next the callaps mine which is all under ground and the out side is covered in bed rock with only one entrence these islands only have ore and no mobs so if you have a teleporting mod there pretty good homes.

Last the frozen waste land it's filled with snow golems and ender sheep which drop wool.