Baleful Beehive

Sometimes attributed to the legendary archmage Mordenkainen (though arcane scholars often sharply dispute this), this particular item takes the form of a fist-sized chunk of honeycombed beehive formed of gold.  As an action, the user can speak the hive's command word and throw it to any point within 30 feet, causing a swarm of spectral bees to emerge from the hive and fill a ten-foot cube centered on that point.  The swarm persists for 1 minute.  When the swarm first appears, any creature within its space must make a DC 13 Dexterity saving throw.  On a failed save, the creature suffers 2d10 piercing damage and must immediately use its reaction to move ten feet in a random direction, exiting the swarm if possible.  On a success, the creature suffers half that damage instead and is not forced to move, though they may choose to use their reaction to move up to ten feet in any direction if they desire.  A creature which uses this movement must try to exit the swarm's space with it.

When a creature begins its turn in the swarm's space or enters it for the first time during their turn, they must repeat the Dexterity saving throw.

When you throw this item, roll a d20.  On a 1, the hive is thrown and lands as normal, but the swarm immediately moves to your location and treats you as its center point.  The swarm moves with you, and you automatically fail your Dexterity saving throws against its effects for the swarm's duration.  Any creature which enters the swarm's space as a result of your movement must immediately make a saving throw against its effects.  If you fall to 0 HP during this duration, the bees immediately return to their hive and disappear.

Regardless of the d20 roll, the hive cannot be used again until the next dawn.