You have mastered your ability to shape change into 1 specific beast and learned to grant yourself extra benefits. Albeit studying the animal or shape changing into the beast regularly. 

 (This feat can be taken multiple times, but a new beast must be chosen each time)

 Choose 1 beast

-While shape changed into this beast, you can use your own Str, Dex, and Con. If the beasts stat is higher you can still use its stats.

-If you have the toughness feat you may add the extra hit points to your wild shape form as well.

-For this beast, its hit dice are equal to the base creature or your druid level, which ever is higher.