When you damage a creature with an attack or a spell and the creature’s size is larger than yours, you can cause the attack or spell to deal extra damage to the creature. The extra damage equals your level. Once you use this trait, you can’t use it again until you finish a short or long rest.

You can take the Disengage or Hide action as a bonus action on each of your turns. Nimble escape makes you kinda rogue or monk like!

The fiend can use its action to polymorph into a Small or Medium humanoid must be the same height, or back into its true form. Without wings, the fiend loses its flying speed. Other than its size and speed, its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

You breath out a pink cloud that charms all creatures in a 25ft cone creatures that fail a wisdom save are charmed are 1d4 hours

You get common gob infernal draconic 

Gem dragonborn can send telepathic messages. Gem dragons are known for their psionic abilities. As a gem dragonborn, you can use Psionic Mind to communicate with creatures within 30 feet. So long as they can comprehend at least one language, they can understand you.

You have a beautiful set of wings that match your dragon type or succubus that let you fly 40

You have Resistance to thunder damage and have a breath weapon