Source: The Book of Many Things

Wondrous Item, rare (requires attunement)

Each of these black leg guards is decorated with a motif of monstrous skulls screaming in terror.

The greaves have 3 charges. While wearing these greaves, you can use a bonus action to expend 1 charge to increase your walking speed by 30 feet, and you have advantage on Dexterity saving throws. These effects last for 1 minute. The greaves regain 1d3 expended charges daily at dawn.

Curse. The greaves are cursed, and becoming attuned to them extends the curse to you. You can’t remove the greaves or end your attunement to them until you are targeted by a Remove Curse spell or similar magic.

You have disadvantage on saving throws against the frightened condition. Whenever you start your turn frightened, the greaves release an ear-piercing scream. You and each creature within 10 feet of you must make a DC 15 Constitution saving throw, taking 9 (2d8) thunder damage on a failed save, or half as much damage on a successful one.