A stroke of lightning forming a 100-foot-long, 5-foot-wide Line blasts out from you in a direction you choose. Each creature in the Line makes a Dexterity saving throw, taking 8d6 Lightning damage on a failed save or half as much damage on a successful one. Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 3.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.