Bloodvenom Vial

Wondrous item, uncommon (requires attunement)

To attune to this vial, you must place a few drops of your blood into it.

As an action, you can activate this item. Once activated, your blood becomes venomous to others for one hour. You gain 5 temporary hit points for the duration. If a creature hits you with a melee attack while you have these hit points, the creature takes 5 poison damage. You must complete a long rest before using this item again.