Each series of 100 breeds will have a "Lucky Breed", for eg: when the breed count is between 1-100 there will be a lucky breed, similarly, between 101-200 there will be another lucky breed and so on.
Lucky Breeds will always have at least one rare body part on the offspring Cryptonite. Also, the rarity of a lucky breed will be 1+ from the rarity of a regular breed.
Eg: If Epic and Common are breeding and the regular rarity is Epic then the rarity for a lucky breed will be Legendary (Epic + 1)
Some Rare Body Parts
The Breeding Arena will be highlighted whenever there is a chance to get a "Lucky Breed" from breeding.
Bubbly Breeding Arena when the user has a chance to get a lucky breed
If you are just too lucky, you might get more than 1 rare type of body part in your lucky breed. The probability of any body part being selected for “rare type” will be equal among all body parts.
The below framework will deduce how many body parts should be rare in any lucky breed.
Probability Framework for Rare Body parts in lucky breed