Magic weapon (sword), artifact (requires attunement)
• You have advantage on attack rolls with this magic weapon and it deals 4d8 radiant damage.
• When you attack a creature whose size is large or smaller with this weapon and roll a 20 on the attack roll, you cut the creature in half and dies. A creature is immune to this effect if it has legendary actions. Such a creature instead takes an extra 4d8 radiant damage from the hit.