You gain a +2 bonus to attack and damage rolls made with this magic weapon.

When you hit a celestial with this weapon, the celestial takes an extra 3d6 slashing damage. 

When you roll a natural 17, 18, or 19 on your attack roll with this magic weapon, it deals an additional 1D4 acid damage, 1D6 fire damage, or 1D8 necrotic damage corresponding to the number rolled. On a natural 20 attack roll, the target gains vulnerability to a damage type of the user's choice that this weapon can deal.

Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Damage: Additional, Damage: Acid, Damage: Fire, Damage: Necrotic, Damage, Combat, Versatile, Sap