Created by the fallen blood of True Dragons, the Kobolds carry the potential once embodied by these mythic begins.  Through age, research, meditation, or happenstance, you have unlocked a fraction of the ability of the true dragons, a breath weapon.  The Kobold can use a breath weapon a number of times equal to their proficiency bonus.  This breath weapon is a 15ft cone that deals 3d6 Thunder Damage.  The save DC is equal to 10 + proficiency bonus + Constitution modifier.    In addition, the kobold gains resistance to Thunder damage.  The breath weapon uses recharge after a long rest.

At 11th level, the damage increases to 5d6, and at 17th level, it increases to 7d6.

 The Kobold's scales change to Sapphire.