Elemental Prodigy

The boisterous powers of the elements are running through your veins. Choose one of the following damage types: Acid, Cold, Fire, Lightning, Poison, or Thunder. 
You gain the following benefits: 

-Choose 1 Cantrip from any spell list, that is related to one of the damage types. You can cast the spell using your spell casting modifier. If you are not a spellcaster, you can choose a spell that doesn't require a saving throw or spell attack role, e.g. Control Flames/Fire, Booming Blade/Thunder, or others to your DMs discretion, like Shape Water/Cold, Thaumaturgy/Fire or Thunder, Druidcraft/Prestidigitation/Cold or Fire. 
-As a reaction when you take damage, you can rebuke your foes. You deal an amount of damage of the chosen type equal to your spell casting modifier, or constitution modifier if you are not a spellcaster, to a number of creatures of your choice equal to your proficiency bonus within a range of 5 feet multiplied by your proficiency bonus.