Wondrous Item, rare
On a hit, this magical ammunition shatters to automatically hit ANY creature within a 10 foot radius of the target. Each creature within 10 feet of the target (NOT INCLUDING THE TARGET) can make a DC15 Dexterity saving throw. On a failure, they take damage equal to the damage against the target. On a success, the creatures will only take half damage. The type of damage dealt to additional creatures is the same as the original target.
Once the ammunition hits, it is no longer magical. This ammunition only counts as hitting one target -- the additional creatures do not count as a target. The ammunition will hit any target -- friend or foe.