A beam of crackling energy lances toward a creature within range, forming a sustained arc of lightning between you and the target. Make a ranged spell attack against it. On a hit, the target takes 2d12 Lightning damage.
On each of your subsequent turns, you can take a Bonus Action to deal 1d12 Lightning damage to the target automatically, even if the first attack missed.
The spell ends if the target is ever outside the spell's range or if it has Total Cover from you.
Using a Higher-Level Spell Slot. The initial damage increases by 1d12 for each spell slot level above 1.
You absorb a measure of a creature's suffering and escaping vital essence. Expend and roll one Hit Points Die. You regain a number of Hit Points equal to the number rolled plus your spellcasting ability modifier.
If the creature took damage from a Critical Hit, double the number of Hit Points you regain.
Using a Higher-Level Spell Slot. You can expend one additional Hit Points Die for each spell slot level above 1.