Voltic Strike

Crackling energy covers your weapon, sheathing it in electricity for the duration, granting the next weapon attack you make advantage against creatures wearing metal armor or metal creatures such as constructs.  While this spell is active, add your Spellcasting ability modifier to the attack and damage rolls of the next weapon attack you make. When you hit a creature with a melee weapon attack while this spell is active, the attack deals an additional 1d10 Lightning damage. Then, 3 bolts of Lightning arc from the target to up to 3 creatures within 15 feet of the target. Each bolt deals 1d10 Lightning damage and can target any creature within range, including the original target. 

When you cast this spell using a spell slot of 4th level or higher, an additional bolt is formed from after the strike for each spell slot level used above 3rd.