Step through Darkness. Vile Blade can use the darkness of the void to travel vast distances instantly. One per round as part of Vile Blade move action, Vile Blade may step into any zone of magical darkness and reappear at another point within a zone of magical darkness within 60 ft.

Maddening Curse. Creatures who are within 30ft of the presence of the Hollow must make a DC 16 Charisma saving throw, on fail the creature is afflicted by 1d12 madness, if a creature has 6 madness or higher they are afflicted by 2d12. 

Shroud of Nothingness. Vile Blade becomes invisible while in magical darkness or heavily obscured.

Frost And Abyss. Vile Blade emits a 5ft radius of frost and decay. Any creature that starts its turn within this radius must make a DC 18 Con save or take 2d4 Cold and Necrotic Damage. If a creature fails by 5 or more they become petrified in ice for 1 turns and is afflicted by Rot their max hit points are reduced by damage taken. Rot is cleansed upon a medicine check exceeding max hit points lost - 5 (minimum of 5 and max of 20).

Dominate Madman. Any creature that starts their turn within 60ft of the Vile Blade with more than 5 madness they must succeed a DC equal to their Madness level Con save or take 1d4 Necrotic Damage and madness. If a creature starts their turn with 20 madness they must make a DC 15 Charisma save or be dominated for 1 turn.

Multi Attack. Hollow makes two attacks from the follow:

Great Sword Slash. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit:2d6+7 slashing damage.

Great Sword Thrust. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 1d10+7 piercing damage.

Special abilities:

Great Sword Execute (5-6). Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 2d10 slashing damage. A creature struck by this that is or dropped below half their max hit points by this attack must make a Con save equal to Damage taken or be instantly killed.

Giants Strength (5-6). unarmed Attack: +14 to hit, reach 5 ft., one target. Hit: 1d4 +7 bludgeoning damage. Creature must make a strength contest against the vile blade or be thrown 15ft in a direction.

Void Surge (5-6). As a bonus action Vile blade can imbue a attack void energy, creature struck by this attack must succeed a DC 14 Charisma save or take 6d6 damage and madness.

Frozen Spear (5-6). Ranged Weapon Attack: +11 to hit, range 60/120 ft., one target. Hit: 1d8 + 11 piercing damage, creature struck must make a DC 12 Con save, On fail they take 2d4 Cold damage. If a creature fails by 5 or more they become petrified in ice for until the end of their next turn.

Corrupting permafrost (6). Vile Blade touches the ground and extends its Frost and Abyss aura outwards in a 15ft cone , All creatures within that space must succeed a DC 12 Con save, On fail they take 4d6 Cold damage. If a creature fails by 5 or more they become petrified in ice for until the end of their next turn and is afflicted by Rot their max hit points are reduced by damage taken. Rot is cleansed upon a medicine check exceeding max hit points lost - 5 (minimum of 5 and max of 20).

Abyssal Aura. when a creature makes an opportunity attack against Vile Blade and misses, Vile Blade as a reaction to deals 6d4 damage the triggering attacker.

Parry (5-6). When another creature damages Vile blade with a melee attack, Vile Blade can use your reaction and roll 2d12 +18 to reduce the damage. If the damage reaches 0, Vile Blade can make a Great Sword Slash attack against the attacker with a bonus to damage and hit equaling the remaining total value they rolled.