Fang Keeper (Patreon)

Wondrous item, rare (requires attunement)

A fang keeper is a dark silver necklace that's adorned with one or more monstrous fangs. When found, the necklace has 1d4 fangs, which come from one or more creatures with a challenge rating of 1 or lower. Over the course of 1 hour, which can be done during a short rest, you can add one or more teeth to the chain or replace any teeth currently on it; the chain can have no more than 4 teeth on it at a time. While wearing the necklace, you gain the following benefits.

Bite. Your teeth lengthen and sharpen slightly; your bite becomes a magic natural weapon, which you can use to make unarmed strikes. If you hit with it, you deal piercing damage equal to 1d8 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike. If you bite a target in this way, you can immediately use your bonus action to clamp down even harder, dealing an extra 1d4 piercing damage to the target as part of the same attack.

Spectral Maw. As a bonus action, you can choose a tooth on the necklace. If the tooth came from a creature that had the Bite action, it summons the spectral maw of that creature in front of you, which is instantaneous. Make a melee spell attack with the spectral maw; the spell attack bonus and damage depends on the challenge rating of the creature the tooth came from. If the attack hits, the tooth immediately rots after the attack, and it can't be used again to summon the maw. On a miss, there's a 50 percent chance that the tooth rots instead.

Once a tooth rots, that same creature's maw can't be summoned again. If another tooth on the necklace is from a creature whose maw has already been summoned in this way, it immediately rots.

One from a troll and one from a snake,

One from a dragon yet all mine to take.

All brought together, all in a line,

Eternally changing, this smile of mine.