My DM is letting a few of us create custom spells for our campaign, and I thought I would run my current idea by some people. The main thing I'm curious about is if the level is balanced with the effect and if my changes to its base (the Thunder Step spell) are balanced with other spells of its level.
Casting Time: 1 action
Range: 90 feet
You teleport yourself to an unoccupied space you can see within range. Upon arrival the air ignites around you, forcing each creature within 10 feet of you except yourself to make a Dexterity saving throw, taking 3d12 fire damage on a failed save, or half as much damage on a successful one. Flammable objects in the same area ignite if they aren't being worn or carried.
At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d12 for each slot level above 3rd.
As stated earlier, this is based off of the Thunder Step spell. I figure changing the "thunder can be heard from up to 300 feet away" as a side effect to igniting objects is an equal change, but I hoped to trade off being able to take someone with me when I teleport to an increase in damage dice. I don't know if changing the damage happening at the endpoint of the teleport affects the level it would be.