Chromatic Shroud

You coat yourself in an aura of elemental energy. Choose acid, cold, fire, lightning, poison, or thunder damage. For the duration, whenever you deal damage within 10 feet of you, you deal an additional 1d6 damage of the type you chose, or 2d6 if it's a melee weapon attack.

In addition, whenever a creature comes within 5 feet of you, or starts their turn there, they must make a Dexterity saving throw. They take 2d6 damage of the type that you chose on a failure, or half as much on a succes. Also, when a creature hits you with a melee attack, they take 1d6 damage of the chosen type.

1 minute after you cast the spell, or upon failing a concentration saving throw, the spell continues, but you take 1d6 damage of the type that you chose at the start of each of your turns. 

You can end the spell with an action. When the spell ends, either by your action or by failing concentration saving throws, the elemental energy erupts from you. Each creature within 15 feet of you must make a Dexterity saving throw. On a failure, they take 3d6 damage of the type that you chose and are knocked back 10 feet. On a succes, they take half damage and are not knocked back. If the spell ended due to you losing concentration, you must do the saving throw as well, taking damage as appropiate and gaining one level of exhaustion.

At higher levels: When you cast this spell at higher levels, the damage dice changes depending on the level of the spell slot used. When you use a 5th level spell slot all dices turn to d8. When you use a 7th level spell slot all dices turn to d10. When you use a 9th level spell slot all dices turn to d12.