Ring of Splitting

The Ring of Splitting is a Rare magic item. A gold ring with a tiny mirror inset into it. Somehow acquired by the Cult of Dragons, it is now in the possession of Sigrant Croffo, even if he currently does not know how to use it. It never becomes dirty, and its mirror is always perfectly reflective, even when broken.

Use
Upon putting it on, the mirror immediately shatters, and the wearer feels their party begin to fall apart. If the user resists it, they must pass a DC 22 Con Save to ensure nothing happens. If the user does not resist it or fails the save, their body transforms into a swarm of a creature that should have some significance to the player's race or class (a frogfolk would burst into frogs, a dragonborn into lizards, a warlock/witch becomes cats or bats, etc) as well as 1d4+1 individual instances of that creature that spawn in spaces right next to the user. If the user was unaware of the effects of the ring, they must pass a DC 15 Wis Save or they will lose control of the individual creatures. If they keep control over themselves, they can control the creatures for 10 minutes. Afterwards the creatures lose sentience and wander off. If all of the creatures are gathered back into the swarm, the user is restored. The ring remains broken for 24 hours, afterwards it will magically repair itself. For every creature lost (through death or just wandering off) the user loses 1/5 HP when they re-constitute.

History
The Ring of Splitting was crafted by Giants during the War of the Trees to allow themselves easy entry into the Feywild as normal humans. They would send a spy into the Feywild to destroy Fleetwood Glades, heavily weakening the fairy leylines and letting their troops advance. Due to this, fairies know not to trust anyone wearing the ring.