When you attack a creature with this magic weapon and roll a 20 on the attack roll, that target takes an extra 10 necrotic damage if it isn't a construct or an undead. You also gain 10 temporary hit points.
Note: According to the SRD, it is an extra 3d6 necrotic damage, although this is incorrect.
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.
When you attack a creature with this magic weapon and roll a 20 on the d20 for the attack roll, that target takes an extra 15 Necrotic damage if it isn't a Construct or an Undead, and you gain Temporary Hit Points equal to the amount of Necrotic damage taken.
You have Disadvantage on attack rolls with a Heavy weapon if it's a Melee weapon and your Strength score isn't at least 13 or if it's a Ranged weapon and your Dexterity score isn't at least 13.
A Two-Handed weapon requires two hands when you attack with it.
If your attack roll with this weapon misses a creature, you can deal damage to that creature equal to the ability modifier you used to make the attack roll. This damage is the same type dealt by the weapon, and the damage can be increased only by increasing the ability modifier.