Thunder Stigma

You channel a volatile charge into a single creature you can see within range, marking it with a Thunder Sigil that makes the air around it highly susceptible to electrical current.

Until the spell ends, Immediately after the target is hit by a successful attack roll that deals Lightning Damage, the target takes an extra 1d4 Thunder damage and a thunderous crack can be heard up to 100 ft. away.

If the target drops to 0 hit points before this spell ends, you can use a bonus action on a subsequent turn of yours to apply the spell to a new creature.

Using a Higher-Level Spell Slot. Your Concentration can last longer with a spell slot of level 2 (up to 4 hours), 3–4 (up to 8 hours), or 5+ (24 hours).