Arlus' Booming Orb

“So, I was working with this wizard, and I saw him cast a certain spell. I think he called it Burning Sphere or something similar- either way, I saw the way it slowly chased things across the area, and I immediately had an idea. Thunder always follows lightning, right? I decided to make it a bit more literal.”  - Arlus Licht, being asked about the spells he pioneered in an interview

You raise your hand to the sky and snap your fingers. A bolt of lightning strikes a target within 60 feet of you, marking them with a crackling brand. The target must make a Dexterity saving throw, or take 2d10 lightning damage. Immediately after, you hold out the glass orb, which gathers and coalesces the thunder from the lightning bolt into a rumbling orb around 5 feet in diameter. This orb will move towards the target marked by the brand. It begins at 40 feet away from the creature, and floats10 feet towards them every round, taking the shortest route possible. If it reaches an adjacent space to the target, it will detonate and release the trapped thunder. Every creature within a 30-foot radius sphere must make a Constitution saving throw or take 9d6 thunder damage and be launched 20 feet away from the sphere. The crackling brand can be transferred from creature to creature if the affected creature makes a melee attack against a creature that did not cast the spell. The orb can be attacked, having an AC of 16 and 5d6 HP. If its HP reaches 0, it will detonate prematurely. The orb cannot be damaged by area-of-effect attacks.

At Higher Levels: When you cast this spell using a spell slot of 6th level or higher, the damage dealt by the lightning bolt increases by 1d10 per level and the damage dealt by the orb increases by 1d6 for each level above 6th.