A ball of lightning forms in the air before you,  crackling with energy. The ball forms in an unoccupied space within range, and is considered a Small object with resistance to all damage, immunity to lightning damage, AC 30, and 6 hit points. It lasts for the duration, until its last charge is expended, or until it is reduced to 0 hit points. When the ball is created, it has 30 charges. You can expend these charges to produce effects;

Lightning Bolt(-1 Charge). You expend 1 charge to cast lightning bolt at its lowest level. When you do this, you can expend additional charges to increase the spell's level by 1 per charge expended.

Chain Lightning(-6 charges). You expend 6 charges to cast chain lightning at its lowest level. When you do this, you can expend additional charges to increase the spell's level by 1 per charge expended.

Dual Lightning(-3 charges). When you cast a spell that deals lightning damage, you can choose to give it the "Twinned Spell" effect from the sorcerer's Metamagic feature without needing Metamagic points. The spell must fulfill all the requirements of Twinned Spell in order to do this.

Lightning Blast(Varies). You expend charges to send a blast of lightning at a creature within 120 feet. Make a ranged spell attack against that creature; on a hit, it takes (1d8 for (each charge you expended+5)+ your spellcasting modifier lightning damage. Make a line extending from you to that creature. Creatures in the line must make a Dexterity saving throw; on a failed save, they take 1d6 lightning damage for each charge you expended. On a successful save, they take no damage.

Lightning Explosion(Varies). When the ball is reduced to 0 hit points or you choose to trigger this as a bonus action, the ball violently explodes into energy, ending the spell. Creatures other that you within a sphere with a radius equal to (2x the charges the ball had when it exploded, minimum 20) ft must make a Dexterity saving throw. On a failed save, they take a number of D12 s of damage equal to (the number of charges the ball had when it exploded, minimum 10). 

Using a Higher-Level Spell Slot. The number of charges increases by 15 and the duration increases by 5 minutes for each spell slot level above 8th.