Every dragon has a maximum number of each Perk type that can be attached to it, based on the dragon’s rarity. Each Perk attached will add a small boost to the existing breeding boost that is currently impacted only by parent rarity and Empowerment.

 The total breeding boost is indicated by the breeding bar in your breeding locations, with green representing the impact of rarity + Empowerment, and yellow representing the addition of the Breeding Boost Perk.