Life Steal. When Zynthedenth kills a creature, he heals for 1d10 health.

Light Sensitivity. While in direct sunlight, Zynthedenth has disadvantage on saving throws, ability checks, and attack rolls.

Turn Undead Immunity. Zynthedenth is immune to all effects that turn undead.

Deadly Aura. All creatures within 5 ft. of Zynthedenth take 2d6 necrotic damage a the start of their turns or when Zynthedenth is hit with a melee attack.

True Invisibility. Zynthedenth can use a bonus action to become completely invisible. Zynthedenth is hidden even from invisibility piercing effects such as see invisibility or truesight..

Unsurprisable. This creature cannot be surprised and gets a +5 bonus to initiative.

Magic Weapons. Zynthedenth’s weapon attacks are magical

True Strike Aura. All creatures within 30ft. have disadvantage on ranged attack rolls made against this creature. This creature has advantage on attack rolls against creatures further than 5ft. away but less than 30ft. away.

Soul Draining. When a creature is damaged by one of Zynthedenth’s attacks, their hit point maximum is reduced by 1d6. This can be undone with greater restoration or similar effects.

Action Surge (3/day). Zynthenth can choose to take one additional action on his turn. This ability can only be used once per turn.

Magic Resistance. Zynthedenth has advantage on saving throws against spells and other magical effects.

Legendary Resistance. (3/Day. If Zynthedenth fails a saving throw, he can choose to succeed instead.

Antimagic Cone. Zynthedenth can use a free action to enable or disable an antimagic cone that extends in a 20ft. cone from Zynthedenth's gemstone eye. This creature and any magical effects created by this creature are unaffected by this cone.

Antiantimagic. Zynthedenth is immune to all anti magic effects.

Uncanny Reaction. Zynthedenth can perform three reactions per round.

Necrotic Concentration (1/day). When Zynthedenth's hit points are reduced to one fourth of his maximum hit points (168 hit points), Zynthedenth absorbs the necrotic mist that normally swirls around him, making him more powerful. Zynthedenth can contain the mist within himself for up to six minutes, and doing so requires concentration. When Zynthedenth enables this effect, he gains 55 (10d10) temporary hit points. Additionally, he gains several benefits while this ability is active:

• His Deadly Aura trait is disabled
• He can use Special actions and abilities.
• He regains 20 (8d4) hit points at the start of every one of his turns.
• He has advantage on Wisdom (Perception) checks
• He gains a +1 bonus to hit and damage rolls
• He has a +2 to AC and all saving throws.
• His save DC increases by +2.
• He deals a critical hit when rolling an 18, 19, or 20.

Weapon Summoning. Once Zynthedenth's hit points are reduced to half of his maximum, he gains the ability to summon spectral weapons in his off hand. A weapon can be summoned once per turn, and disappears at the start of his next turn. The same weapon cannot be summoned for two turns in a row. Different weapons allow Zynthedenth to perform special actions and attacks.

• Scythe. Creates a soulsteel scythe in his off hand and uses it to make a melee attack.
  • (Soulsteel). Melee Weapon Attack: +14 to hit, reach 10ft., 1 target. Hit: 21 (6d6) slashing plus 28 (8d6) necrotic damage. On a hit, the target must succeed on a DC 24 Wisdom saving throw, or have their maximum health reduced by 26 (4d12).
  • Zynthedenth spins the scythe in a circle. All creatures within 10 ft. must make a DC 22 Dexterity saving throw, taking 52 (5d20) force plus 42 (4d20) necrotic damage on a failed save, or half as much on a success.
• Spear. Creates a soulsteel spear in his offhand, and can use it to make a melee attack, or can throw it at a creature.
  • Ranged Weapon Attack: +14 to hit, range 40ft., 1 target. Hit: 52 (5d20) piercing damage. Creates a soulsteel spear in his off hand and flings it at the target. On a hit, the impaled target takes 8 (1d12 + 2) necrotic damage at the start of every one of their turns until the spear is removed. To remove the spear the creature must use a bonus action and succeed on a DC 18 Str saving throw.
  • (Soulsteel). Melee Weapon Attack: +14 to hit, reach 10ft., 1 target. Hit: 35 (10d6) piercing plus 14 (4d6) necrotic damage. If Zynthedenth moves 10ft. or more towards the target before making the attack, the attack deals an additional 14 (4d6) force damage.
• Sword. Creates a sword in his off hand and uses it to perform an extra attack. This weapon can be used to perform an advanced multiattack.
  • Multiattack: Zynthedenth makes four soulsteel attacks, two strong attacks, or one strong attack and two soulsteel attacks.
• Hammer. Creates a hammer in his off hand and either slams it into a target in front of him or jumps into the air and does a groundpound attack
  • Melee Weapon Attack: +13 to hit, range 5ft., 1 target. Hit: 77 (14d10) bludgeoning plus 22 (4d10) necrotic damage, and the creature must succeed on a DC 15 Str saving throw or be stunned until the start of Zynthedenth's next turn.
  • Zynthedenth jumps into the air, and then slams the hammer into the ground, creating an eruption of ground around him. All creatures within a 20 ft. sphere must make a DC 19 Dex saving throw, or take 108 (24d8) bludgeoning damage and be knocked prone.
• Crossbow. Creates a hand crossbow in his off hand, which can be shot.
  • (Soulsteel). Ranged Weapon Attack: +14 to hit, range 200/600ft., 1 target. Hit: 22 (4d10) piercing damage. Fires the crossbow two times in quick succession, making a separate attack roll for each shot.
• Necrotic Orb. Creates an orb of necrotic energy, which floats just above his off hand. The orb cannot be used to make any attacks, but instead enhances Zynthedenth's soulsteel attacks. While the orb is summoned, Zynthedenth's soulsteel attacks deal an additional 16 (3d10) necrotic damage.
• Staff. Creates a staff, which he wields in his off hand. The staff cannot be used to make any attacks, but instead enchances Zynthedenth's spellcasting ability. While the staff is summoned, Zynthedeth gets a +2 to his spellcasting to hit bonus, and a +2 to spell save DCs. Additionally, all spells that deal necrotic damage also apply soul rend.

Necrotic Spellcasting. All spells cast by Zynthedenth that deal radiant damage deal necrotic damage instead.

Spellcasting. Zynthedenth is a 20th spellcaster. His spellcasting ability is Intelligence (spell save DC 22, +14 to hit with spell attacks). Zynthedenth has the following spells prepared:

• (3 slots each): All cantrips-6th level spells
• (2 slots): All seventh level spells except simulacrum
• (1 slot): All eighth level spells except clone
• (1 slot): Every ninth level spell except wish.

Multiattack. Zynthedenth makes three soulsteel attacks, or one strong attack and one soulsteel attack.

Soul Orb. Ranged Weapon Attack: +14 to hit, range 300/500 ft., 10ft sphere. Hit: 52 (8d10 + 8) psychic damage plus 22 (5d8) necrotic damage. On a hit, the creature becomes cursed. The curse disrupts their thoughts with horrible nightmares. While cursed, the creature gains no benefits from short or long rests. If a short or long rest is attempted, the creature must succeed on a DC 19 Wis saving throw or take 26 (4d12) physic damage. After three failures, the creature becomes under the permanent control of Zynthedenth. The curse lasts for 14 (2d8 + 5) days or until otherwise removed.

Soulsteel Slash (Soulsteel). Melee Weapon Attack: +14 to hit, range 5ft., 1 target. Hit: 27 (6d8) slashing plus 13 (3d8) necrotic damage. Creates a soulsteel sword in his off hand, which Zynthedenth then uses to make a slashing attack, then dissipates.

Necoritc Arc (Soulsteel). While holding a soulsteel sword, Zynthedenth swings it, causing it to shoot out an arc of necrotic energy. The arc travels up to 60 ft. before dissipating. Any creature it hits must succeed on a DC 20 Dex saving throw or take 32 (5d12) necrotic damage. A creature hit by this attack must succeed on a DC 17 Wis saving throw or be afflicted with soul rend.

Sword Slam (Strong). Zynthedenth slams his soulsteel sword into the ground, and an eruption of earth will spike up in a 30 ft. line. All creatures within the line must make a DC 16 Dex saving throw, taking 78 (12d12) bludgeoning damage and being knocked prine on a failure, or taking half damage on a success.

Soulsteel Grab (Strong). Melee Weapon Attack: Zynthedenth reaches out and grabs a creature within 5 ft., and the creature must succeed on a DC 19 Dex saving throw. On a failure, Zythedenth flings the creature into the air, and then thrusts his sword into their stomach. The creature takes 38 (7d10) piercing plus 22 (4d10) necrotic damage and becomes afflicted with soul rend, and then falls prone.

Chasing Cuts. Zynthedenth dashes up to 300 ft. towards a creature within 300 ft. that is not touching the ground. Zynthedenth then makes six soulsteel slash attacks against the creature. For each hit, the target must succeed on a DC 19 Strength saving throw or be knocked prone. Zynthedenth then drops to the ground, and doesn't take any fall damage.

Ultra Soul Blast. Spell Attack: (3/day):  Every time Zynthedenth deals 50 damage, he gains a charge point. He must have at least one charge point to use this ability, and using it expends all charges. Zynthedenth releases a blast of charged up necrotic energy, annihilating anything in sight. All creatures not friendly to Zynthedenth within charge * 10 ft. must succeed on a DC 15 + charges Wis saving throw or take charge * 1d10 necrotic plus charge * 1d10 force damage. If a target fails the saving throw by 5 or more, they are blasted 1d6 * 5ft away and knocked prone.

Release Death. All bones or corpses of creatures within 60 ft. become animated undead and under this creature’s control.

Corrupting Whisper. Zynthedenth telepathicly whispers quietly into the ear of its target, speaking about their deepest desires and persuading them to join him. They must succeed on a DC 19 Wis saving throw or be under Zynthednth’s control for 1 day. If the controlled creature is forced to attack something they think friendly, they are able to reroll the saving throw. The spell ends on a success. 

Special Attacks. While imbued with necrotic mists, Zynthedenth can perform the following special attacks:

• Misty Strike (Strong). Zynthedenth releases a cloud of mist, which occupies a 30 ft. sphere around him and heavily obscures vision, causing all other creatures within the area to have Disadvantage on Wisdom (Perception) checks related to sight. Zynthedenth then can use up to all of his movement speed to move towards a target, and makes a soulsteel melee weapon attack against the target. The attack has advantage to hit, deals an additional 44 (8d10) damage, and crits from a 14-20.

Uncanny Dodge. When an attack would hit Zynthedenth, he can choose to use his reaction to attempt a DC 16 Dexterity saving throw. On a success, Zynthedenth takes no damage from the attack, and he takes half damage on a failure.

Parry. When a creature would hit Zynthedenth with a melee weapon attack, he can choose to use his reaction to add a +4 bonus to his AC for the duration of the attack. If this causes the attack to miss, then Zynthedenth can make a counterattack, choosing a Soulsteel melee weapon attack. He performs this attack at the end of the creature's turn, as though using a Legendary Action.

Zynthedenth can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. This creature regains spent legendary actions at the start of its turn.

Soul Slash. Zynthedenth uses a soulsteel attack

Spell. Zynthedenth casts a spell of 5th level or lower, that has a casting time of one action or bonus action.

Summoned Weapon. Zynthedenth makes an attack with a weapon he has summoned in his off hand. Using this legendary action costs 1 legendary action if it is a soulsteel attack, 2 if it is a strong attack, or 3 if the attack requires an action.

Necrotic Spears. (Costs 3 Actions). Zynthedenth summons six spears of necrotic energy, and flings them at up to six creatures. For each creature hit, make an attack roll against that creature. +13 to hit, range 120 ft. Hit: 13 (3d8) piercing + 9 (2d8) necrotic damage.