Sonar Arrow (Patreon)

Weapon (arrow), rare

This long, dark arrow looks as though it's been pierced through a bat. A target hit by this arrow takes an extra 2d10 thunder damage. Hit or miss, when the arrow first impacts with a creature, object, or other solid surface, it emits a brief, magical frequency, which is audible out to a range of 120 feet. Every creature that isn't deafened within the sound's range magically knows the location of every other physical creature and any obvious, uncovered object within the frequency's area at that moment. The arrow then loses its magic and becomes a normal arrow.

A creature that has the Keen Hearing trait gains a +5 bonus to any Wisdom (Perception) check it makes until the end of its next turn after hearing the frequency. If the arrow hits a creature with this trait, it takes an extra 3d10 thunder damage from the attack, instead of 2d10.

Other types of magic ammunition of this kind exist, such as sonar bolts meant for a crossbow, though arrows are most common.

Bastan and his werepack had been watching the old shack for the last 3 days, and none but the old man had come or gone. They made their move after nightfall, trusting their superior senses to lead them to their prey.

PING

An arrow nicked his shoulder, bringing with it an earsplitting sound. Bastan reeled as for the briefest moment he seemed to hear everything around him. The grass under his paws, his packmates circling the shack, and the old man, watching them from the window, longbow in hand.

When his ears stopped ringing, Bastan heard the old man speak.

"I counted 4 heads, so, unless you've 6 more friends out of range, there aren't nearly enough of you. I'm going to give you to the count of 5 to get off my land, or the next arrow will hurt a lot more than your ears."