Charging Lightning Bolt

The lightning around you arcs towards you charging your bolt of lightning. When the spell ends, either because your concentration is broken or because you decide to end it, the charged up lightning blasts outward from you in a 100 foot long and 5 feet wide line in a direction you choose. Each creature in the line must make a Dexterity saving throw. A creature takes lightning damage equal to the total accumulated damage on a failed save, or half as much damage on a successful one.

Anytime you take lightning damage the damage of the bolt increases by an amount equal to the lightning  damage you take. If you have resistance or immunity to lightning damage and are concentrating on this spell, anytime you take lightning damage you can temporarily suppress the resistance or immunity for that instance of damage to add it to the damage of this spell.

At the beginning of the spell the damage of the spell increases by 6d6. Holding the energy is damaging to your body, if at the end of your turn the energy has not been released, you take 1d6 lightning damage which is added to the damage of the spell. Any damage you take from this spell does not affect your concentration, but damage taken from other sources can still affect it.

At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, the base damage increases by 1d6 for each slot level above 7th.