Xephy's Bone Arrow

You fire a barbed shard of your own bone at one creature within range. You immediately take 1d6 piercing damage which cannot be resisted.

Uninvited Guest. Make a ranged spell attack against the target. On a hit, a bone dart  pierces and gets hooked into the flesh of the creature and it takes piercing damage equal to 2d6 plus your spell attack modifier and makes a Constitution saving throw. The creature takes 1d10 necrotic damage on a failed save. So long as the bone dart is attached to its flesh, the creature repeats the save at the start of its following turns and takes an additional 1d10 necrotic damage on each failed save. The creature may take an action to pull the bone dart out to stop making saves.

Bring A Plus One. A creature may not have more than one bone dart from the same source attached to it. If another bone dart from the same source hits and attaches to a creature, only the higher spell level of the two is retained and the other does not make a creature take additional damage on failed saves and is considered as having been removed.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the spell does an additional 1d6 necrotic damage on a failed save for each slot above 1st.