Artor Fellbranch, High Warden of Lyrengorn

Magic Items. Artor has Shoonfang and the Plate of the Dread Warden

Shapechanger. If the vampire isn't in sunlight or running water, it can use its action to polymorph into a Tiny bat or a Medium cloud of mist, or back into its true form.

While in bat form, the vampire can't speak, its walking speed is 5 feet, and it has a flying speed of 30 feet. Its statistics, other than its size and speed, are unchanged. Anything it is wearing transforms with it, but nothing it is carrying does. It reverts to its true form if it dies.

While in mist form, Artor can't take any actions, speak, or manipulate objects. It is weightless, has a flying speed of 20 feet, can hover, and can enter a hostile creature's space and stop there. In addition, if air can pass through a space, the mist can do so without squeezing, and it can’t pass through water. It has advantage on Strength, Dexterity, and Constitution saving throws, and it is immune to all nonmagical damage, except the damage it takes from sunlight.

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

Misty Escape. When he drops to 0 hit points outside its resting place, Artor transforms into a cloud of mist (as in the Shapechanger trait) instead of falling unconscious, provided that it isn't in sunlight or running water. If it can't transform, it is destroyed.

While it has 0 hit points in mist form, it can't revert to its vampire form, and it must reach its resting place within 2 hours or be destroyed. Once in its resting place, it reverts to its vampire form. It is then paralyzed until it regains at least 1 hit point. After spending 1 hour in its resting place with 0 hit points, it regains 1 hit point.

Regeneration. Artor regains 20 hit points at the start of its turn if it has at least 1 hit point and isn't in direct sunlight. If Artor takes radiant damage or damage from holy water, this trait doesn't function at the start of Artor's next turn.

Spider Climb. Artor can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Vampire Weaknesses. Artor has the following flaws:

Stake to the Heart. If a piercing weapon made of wood is driven into the vampire's heart while the vampire is incapacitated in its resting place, the vampire is paralyzed until the stake is removed.

Sunlight Hypersensitivity. He takes 20 radiant damage when it starts its turn in sunlight. While in sunlight, it has disadvantage on attack rolls and ability checks.

Multiattack. (Vampire Form Only). Artor makes two attacks with Shoonfang or his warhammer, only one of these attacks can be replaced with a bite

Shoonfang (Double-bladed Greatsword) (Vampire Form Only). Melee Weapon Attack: +12 to hit, reach 5 ft., one creature. Hit: 17 (2d8 + 8) slashing damage plus 7 (2d6) necrotic damage. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and Artor regains hit points equal to that amount. The reduction lasts until the target finishes a long rest or until targeted by the greater restoration spell. The target dies if this effect reduces its hit point maximum to 0.

Warhammer (Vampire Form or Shadow Only). Melee Weapon Attack: +12 to hit, reach 5 ft., one creature. Hit: 10 (1d8 + 6) bludgeoning damage. If the attack roll succeeds by 5 or more, the target must make a DC 16 Constitution saving throw or be stunned until the end of its next turn.

Bite (Bat or Vampire Form Only). Melee Weapon Attack: +12 to hit, reach 5 ft., one willing creature, or a creature that is grappled, incapacitated, stunned, or restrained. Hit: 8 (1d6 + 5) piercing damage plus 14 (4d6) necrotic damage. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and Artor regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. A humanoid slain in this way and then buried in the ground rises the following night as a vampire spawn under the vampire's control.

Charm. Artor targets one humanoid it can see within 30 feet of it. If the target can see Artor, the target must succeed on a DC 17 Wisdom saving throw against this magic or be charmed by him. The charmed target regards Artor as a trusted friend to be heeded and protected. Although the target isn't under the vampire's control, it takes Artor's requests or actions in the most favorable way it can.

Each time the Artor or Artor's companions do anything harmful to the target, it can repeat the saving throw, ending the effect on itself on a success. Otherwise, the effect lasts 24 hours or until Artor is destroyed, is on a different plane of existence than the target, or takes a bonus action to end the effect.

Manifest Shadow(1/Day). As a bonus action Artor can create a duplicate of himself out of shadow. This shadow rolls its own initiative, has half of Artor's maximum hp, has an AC of 14, is vulnerable to radiant damage, and only makes one attack per turn with the warhammer. 

Shadow Step. If not in direct sunlight, Artor can magically teleport as a bonus action, along with any equipment he is wearing or carrying to an unoccupied space he can see within 30 feet.

Shield of Shadow (3/day). As a reaction Artor can summon a shadow for a brief moment in order to take an attack for him. The attacker has disadvantage on their attack. If the attack then misses Artor, the attacker hits the shadow instead and it vanishes.

Artor 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. Artor regains spent legendary actions at the start of his turn.

Shoonfang.(Costs 1 Action). Artor makes an attack with Shoonfang

Strike from Shadow. (Costs 2 Actions). Artor can use his shadow step and make one attack with shoonfang after he teleports, if a target is within range.

Storm of Shadow. (Costs 2 Actions).  Artor summons the shadows around him to lash out at his enemies. Each creature within 30 feet of Artor must make a constitution saving throw DC 18 or take 4d6 necrotic damage and be pushed up to 10 feet away, if a creature succeeds on its saving throw it takes half of the necrotic damage and isn't pushed away.