To cast this spell knowing true triton tongue is necessary.
An eruption of lightning forming a line 80 feet long and 3 feet wide blasts out from your hand with a gust of salty seawater flowing after it in a direction you choose. Each creature in the line must make a Dexterity saving throw. A creature takes 5d4 lightning damage, be pushed back by 3 tiles and gain vulnerability to lightning for 3 rounds on a failed save, or half as much damage and no other negative effects on a successful one.
The lightning ignites flammable objects in the area that aren't being worn or carried. The water puts out any fires created by the lightning.
At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d4 for each slot level above 2rd.