Thor's Envy

Raising an arm up to the sky with a closed fist, and then slamming it down towards the ground, a tattoo of Mjolnir you have on your body crackles with blue energy as the skies above you darken almost instantaneously. From these darkened skies, massive arcs of lightning strike down from the heavens and hit anyone within a 20 ft radius of wherever you specify. The targets make a Dexterity saving throw, and upon failure take 8d6 lightning damage or half that if successful. When cast at higher levels, each bolt of lightning can arc to an additional target outside the initial radius once per spell slot above 3rd. Along with this, when cast at higher levels every target takes an additional d6 thunder damage per spell slot as the cracking thunder follows the initial lightning strike. After the spell is performed, the ground within the 20 ft radius of the spell has the symbol of Mjolnir etched into it.