If you use this sword to attack an enemy from a distance when cloaked you can teleport to that enemy. If you do you get an advantage on the attack and gain 3d6 sneak attack damage. You can also teleport away from an enemy just after attacking it with this sword when cloaked. You can only teleport 30ft and doesn't take up an movement.

 

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

At the start of your turn you can use a bonus action to activate the passive :

Dark cloaked blade to gain +3 to close range attack and damage rolls

Must have dark cloak active to use :

Yami Matoi Jigen Giri(Dark Cloaked Dimension Slash) - Allows you to Roll to fire a dark slash attack from any range in a straight line cutting through all obstacles and does 3d8 dark slashing damage from range or 3d6 sneak attack damage if you choose to teleport  once used dark cloak must be re applied at the start of your next turn using your bonus action

One use per long rest:

Yami Matoi Jigen Giri Higan (Dark Cloaked Dimension Slash Equinox) -  Roll the 2 percentage die if you get between 0-33% the target Instantly vanishes from this dimension reappearing after 12 mins in the same spot. 33-66% target takes 4d8 dark slashing damage. 66-91% target takes 4d12 dark slashing damage and movement is reduced to 0 for 2 turns. 92-99%+ Targets life forced is severed from all realities ending their life instantly everywhere at once.  

 

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

Notes: Damage: Additional, Damage: Necrotic, Damage, Combat, Versatile, Sap