Dragon Aura

You evoke the power of a dragon, creating an aura of energy around you in a vaguely draconic shape. For the duration, you gain temporary hit points equal to three times your spellcasting ability modifier (minimum of 3). Additionally, choose acid, cold, fire, lightning, or poison. Also for the duration, you have resistance to that damage type, and whenever a creature hits you with a melee attack, it takes damage of the chosen type equal to 2d10 + your spellcasting ability modifier. Finally, you can cause the spell to end early as an action. When you do, you release a blast of energy in a 30-ft cone originating from yourself. Each creature in the cone must make a Dexterity saving throw or take damage of the chosen type equal to 2d10 + your spellcasting ability modifier, or half as much damage on a successful save.

At higher levels. When you cast this spell using a spell slot of 5th level of higher, you gain 5 more temporary hit points per slot level above 4th, and all damage dealt by the spell increases by 1d10 for each slot level above 4th.