Where to put Corrupticorn Dragon?

I just became level 31 and I have this Corrupticorn dragon I picked from finishing the Halloween event and I don’t know if I should place him in the Rift or Rainbow Habitat.

I just became level 31 and I have this Corrupticorn dragon I picked from finishing the Halloween event and I don’t know if I should place him in the Rift or Rainbow Habitat.