Talbot's Totem Circle

You plant four skulls in the ground within range and lay magic upon them to protect an area.

Each skull transforms into a piece of nonmagical ammunition; arrows or crossbow bolts. The caster chooses. 

Until the spell ends, whenever a creature, other than you or chosen allies, comes within 30 feet of the ammunition for the first time on a turn or ends its turn there, one piece of ammunition flies up to strike it. The creature must succeed on a Dexterity saving throw or take 2D6 piercing damage and 1D4 necrotic damage. The piece of ammunition is then destroyed. The spell ends when no ammunition remains.