You have undergone a physical evolution and gain the following benefits:

• Increase your Constitution or Dexterity score by 1, to a maximum of 20.
• You grow wings giving you a flying speed of 30 feet. To use this speed, you can’t be wearing medium or heavy armor. At level 11 this increases to 40ft. 
• You can use your wings to slow your fall or allow you to glide. When you fall and aren’t incapacitated, you can subtract up to 40 feet from the fall when calculating falling damage, and you can move up to 2 feet horizontally for every 1 foot you descend. At level 11 this increases to 80 feet.
• When taking damage while flying, make a constitution saving throw (same as spell concentration.) Failure means your wings are injured/tired and you begin a 'falling descent.' At level 11, you no longer need to make these checks as your wings have fully developed and are sturdier.