Delmuth's Piercing Ammunition

You brandish the ammunition used in the spell’s casting. Until the start of your next turn, when the ammunition is used by an appropriate ranged weapon to hit a target with a ranged weapon attack, all creatures 5 feet behind the initial target take piercing damage equal to your spellcasting ability modifier.

This spell’s piercing distance increases when you reach certain levels. At 5th level, the ammunition affects all creatures 10 feet behind the initial target. This increases to 15 feet at 11th level and 20 feet at 17th level.