Conduction

A creature that you can see within range must make either a Charisma or Constitution saving throw. If the target fails this saving throw, they are afflicted with the Conductive status and take an extra d12 of damage when damaged by lightning, fire, or cold (excluding environmental effects). If a creature afflicted with the Conductive status condition is normally resistant or immune to lightning, fire, or cold, they will lose said traits until the status condition is removed. 

At Higher Levels. For each level increase the number of targets that can be selected increases by 1