An Aasimar who has succeeded in fulfilling the purpose they were created may take this feat (Or whenever DM says it's cool). You gain the following benefits:

• Increase your Wisdom or Charisma score by 1, to a maximum of 20.
• You gain Immunity to Necrotic or Radiant Damage. 
• Your wings fully manifest, giving you 40 feet of flying speed permanently. 

Scourge, Protector, and Fallen Aasimars all benefit differently from this feat:

• Fallen Aasimars Necrotic Shroud ability doubles the range to 20 feet as well as doubles the amount of necrotic damage you can deal to twice your proficiency bonus.
• Scourge Aasimars Radiant Consumption ability doubles the range to 20 feet as well as doubles the amount of radiant damage you can deal to twice your proficiency bonus.
• Protector Aasimars Radiant Soul ability doubles how long it lasts to two minutes as well as gives you a flying equal to double your movement speed and doubles the amount of radiant damage you can deal to twice your proficiency bonus.