Wave Strike

You conjure spiraling serpents of pure water to circle a weapon you're holding or a piece of ammunition you have nocked. The next time you hit with an attack using this weapon, the target takes 4d4 additional bludgeoning damage and is knocked back 10 ft., if the target is Large or smaller. If the target is Huge, they are moved 5 ft. and if they are Gargantuan, they are not moved. In addition, the target must make a Strength saving throw or be knocked prone. All non-magical exposed flames within 10 ft. of the target are dowsed. On subsequent turns, you can use your bonus action to summon the water to your weapon again to repeat this strike, dealing 1d4 less damage from the initial strike until it reaches 0, not forcing any movement or requiring any saving throw.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the initial extra damage dealt by the attack increases by 2d4 for each slot.