Soul Eater

Soul Eater flails are very rare weapons created in the Nine Hells in a forgotten time; wielded by the devils to be used against the demons in the blood war. Each such flail can steal a creature's soul if it has one, and store it inside it making it more powerful. Sometimes these flails occasionally find their way into the Material Plane spreading misery, death, and worse.

This hellish flail seems like it has been charred by flames and is still sometimes releasing smoke. If you lean close to it you can hear sounds of people screaming in agony.

Flail (Very Rare)

Requires Attunement

This weapon deals fire damage during the day and necrotic damage during the night. Its base magical damage is 1d10. When a creature that has a soul is killed by this flail, it has its soul absorbed into the flail which is used to power the weapon. Each soul absorbed into the flail increases the weapon’s magic damage by 1d4. The weapon can store up to ten souls.

During an attack made with this flail, you can use all the trapped souls at once to overcharge it and deliver a devastating magical blow accompanied by the loud shrieks of the souls, dealing damage equal to 1d10 x the number of trapped souls + the weapon’s base magical damage. After the attack, the souls are expanded and utterly destroyed either the attack hits or misses. The flail then becomes inactive and loses all of its effects for a day, after which it can again begin harvesting souls.