Nightfall (5e Equipment)
From D&D Wiki
Weapon (longsword), Legendary (requires attunement)
A slightly transparent sword that seems to have a black and blue sheen to it when exposed to light. This sword can be wielded as a magic longsword that grants a +1 bonus to attack and damage rolls made with it.
Honed Edge. Whenever you score a critical hit with this weapon, the damage die is multiplied by three, instead of two. In addition, any attack you make with this weapon against an object is considered a critical hit.
Quick Slash. When you hit a creature with this weapon, you can use your bonus action to make another attack against it.
Shadow Strike. As a bonus action, you can teleport to a unoccupied space within 5 feet of a creature you can see, up to a range of 60 feet. You have advantage on your next attack roll with this weapon against that creature. You can use this property twice, and can't be used again until the next dawn.
Shadow Double. At the start of each of your turns while wielding this sword, you can cause a illusion of you appears on your position (without requiring an action), that lasts until the end of your next turn. This illusion requires a DC 17 Wisdom (Perception) check to discern from your real self. You can use your bonus action to teleport to the illusion's position.
If attuned by a character with a level 17 or higher, you also can cast the spell ephemeral storm. This spell can't be used again until 30 days have passed.