You have a +1 bonus to attack and damage rolls made with this magic weapon.
This greatsword is made of an unknown black metal. In most cases, it works as a +1 greatsword. But when used against a thessalhydra, it works as a +3 greatsword. While in the Upside Down, it works as a +4 greatsword.
Creatures that are Small or Tiny have disadvantage on attack rolls with heavy weapons. A heavy weapon's size and bulk make it too large for a Small or Tiny creature to use effectively.
This weapon requires two hands to use. This property is relevant only when you attack with the weapon, not when you simply hold it.