Atheras's Wildfire

You toss a 4-inch ball of shifting fire towards a target of your choice that you can see within range. Make a ranged spell attack against the target. On a hit, the target takes 5d8 fire damage. On each additional turn, you can use your bonus action to cause the fire to leap from that target to another target within 20 feet, making a new attack role against them. If you do not move the fire, then the target takes 5d8 fire damage at the start of their turn, then the spell ends.

You can continue to use your bonus action to move the fire until it misses, you choose to not move it or you choose to dismiss it on your turn (no action required).

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the initial* damage increases by 1d8 for each slot level above 4th.

*The initial damage applies to the damage dealt when the fire strikes a new target, but not the damage dealt by ending the spell on a target.