Doomsblood

Weapon (sickle), legendary (requires attunement)

Doomsblood was an ancient black dragon whose territory was encroached upon, unknowingly, by an ancient gold dragon raising a youngling.

Doomsblood, feeling disrespected, ambushed the golden dragon known as Mother and fought her.

Although Mother fought bravely and protected her child, she was gravely injured in the process.

Doomsblood, feeling his death was imminent, was forced to retreat. He fled to his lair and passed away, unable to heal from the wounds of battle. Thousands of years later, the remains of Doomsblood were discovered, and a part of his neck with an intact acid sack was harvested and made into this sickle that constantly produces acid.

You gain a +3 bonus to attack and damage rolls made with this magic weapon. When you hit with an attack using this magic sickle, the target takes an extra 1d8 acid damage. In addition, while you are attuned to this weapon, your mind slightly drifts towards darker thoughts and harsher judgements, and you seek to control through dominance.

Once per turn, when you score a critical hit using this magic weapon, you can make another attack with it against the same target or a different one.

While you hold this sickle, you can use an action to have it produce an acidic spray. Each creature in a 15-foot cone must make a DC 18 Dexterity saving throw.

A creature takes 3d6 acid damage on a failed save, or half as much on a successful one. This property of the sickle can’t be used again until you complete a long rest while attuned to it.