The special habitats like rainbow, Egyptian, zombie etc... Where do you find them? when? How do you obtain them? I've been playing for 4 months and haven't even had a chance to get one. (BTW, I'm at level 72, have over 45k master points, over 250 dragons, and am in master leagues, and have spent money on the game.... So what am I missing or not seeing?)

There was an Egyptian habitat available in the last group of events with Horus god dragon.
Rainbow and zombie habitats also came in special events, one last Halloween and the other this past spring sometime, I think

@david-hanson The rainbow habitat is only available if you buy infinite island for cash atm. All others are not available now. You have to wait if they show up again.