I couldn't find a dedicated c/unearthedarcana so I'm posting here. I've been creating a handful of homebrew spells to fit characters I'm playing. For this one I wanted to make a spell for my lighting storm-themed gish character that would also be a nice capstone spell for an Eldritch Knight in general. While there are some similar-ish spells I'm basing it off of, I wanted some feedback if it's balanced based on the damage numbers and amount of benefits for its spell level.
Personal Lightning
4th-level evocation
Casting Time: 1 bonus action
Range: Self
Components: V, S
Duration: Concentration, up to 10 minutes
You channel the energy of a fierce lightning storm within your body. You gain the following benefits until the spell ends:
- Attacks you make deal an extra 1d6 lightning damage on a hit.
- Your speed increases by 20 feet.
- Your movement doesn't provoke opportunity attacks.
- Your jump distance is tripled.
As an action on your turn, you can dismiss this spell and cause a blast of electricity to erupt from you. Each creature within 20 feet of you must make a Constitution saving throw. A creature takes 3d6 lighting damage and 2d6 thunder damage on a failed save, or half as much damage on a successful one.
At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, the thunder damage dealt by the blast increases by 1d6 for each slot level above 5th. Using a spell slot of 6th level or higher also causes you to gain a fly speed of 50 feet until the spell ends.
Edit based on feedback: I'm getting a variety of responses, so I'm figuring out what exactly needs to be targeted for adjustment here. The blast option seems to be considered a bit strong since it's an additional mode to the other benefits. I can shrink the range and drop the damage a little. I don't want to nerf it too much though because it's still costing an action. Maybe drop it down to 15 foot radius and, what, 3 or 4 damage dice?
In terms of the main mode of the spell, I want the spell to compare fairly overall with guardian of nature which is the same level. Guardian has two different modes that both give advantage on (pretty much) all of your attacks; with that in mind I'm considering if it's fair to up the damage dice from my spell to 1d8 per hit. Would that be fair, or am I underrating the other benefits of my spell here?