Once per turn, when you hit a creature with an attack using this magic blade, you can mark the target. On the next attack with this blade the marked target takes an additional 1d4 necrotic damage for each time you've marked it. At the start of the targets turn, it can make a DC 15 Constitution saving throw, ending the effect of all such marks on itself on a success.
Additionally, you can roll a hit die and subtract the total + Constitution modifier from your maximum HP, this HP can not be regained until the next short or long rest. Spending a hit die in a such a way charges the weapon up to 3 times. You can expend all charges as a bonus action to temporarily turn the hand which wields the blade into an alien tentacle which can launch up to a range of 120 feet. The tentacle uses the same attack roll as this blade and does 4d8 force damage per charge. When the blade is at full charges the attack has advantage on the attack roll and can target an additional target. This weapon resets the charges to 0 on a long rest.
This magic blade gains a +1 to attacks rolls and damage rolls.
Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.
This weapon has the following mastery property. To use this property, you must have a feature that lets you use it.
Sap. If you hit a creature with this weapon, that creature has Disadvantage on its next attack roll before the start of your next turn.
Notes: Damage: Necrotic, Bonus: Magic, Damage, Combat, Versatile, Sap