Body of the Storm. While in a thunderstorm, the dragon has advantage on Dexterity (Stealth) checks.
Innate Spellcasting. The dragon’s spellcasting ability is Intelligence (+3 to hit, DC 11). It can innately cast the following spells, requiring no material components:
At will: shocking grasp, thunderclap
1/day each: thunderwave, witch bolt
Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. 6 (1d10 + 1) piercing damage plus 4 (1d8) lightning damage.
Storm Breath (Recharge 5-6). The dragon exhales the power of the storm in a 15-foot cone. Each creature in that area must make a DC 13 Constitution saving throw, taking 9 (2d8) lightning damage plus 13 (3d8) thunder damage on a failure, or half on a success. On a failure, a Large or smaller creature is also pushed back 10 ft.
Enter the description for how legendary actions work for your monster here.
Legendary Action Name (Costs # Actions). Enter the description for your legendary action.
Description
Storm dragons are unique dragons that were created by the forces of elemental chaos. They share many characteristics with blue dragons, but are neutral as opposed to evil. When they fly through the dark clouds of thunderstorms, they appear almost incorporeal, and look as if lightning ran through their veins instead of blood. The elder storm dragons are extremely intelligent, even more than gold dragons, but aren't as physically powerful. Many storm dragons utilize the lighting in their blood to perform powerful magic, and often even create the storms they prefer to fly in.
Any suggestions for improvements or balancing are more than welcome.