Vampire

The vampire is proficient in many abilities, focusing more on movement and taking advantage of situations, rather than dealing damage. However, the vampire will need to feed to satiate their hunger. If they don't, they become more primal and may even turn on their fellow adventurers for sustenance. The following features on imposed on the vampire once they are transformed:

Price of the Damned
All conventional healing has no effect on the vampire anymore. Once transformed, the vampire is now immune to healing spells and healing potions. The only way for the vampire to regain hit points is by regenerating or by feeding.

Undead Aspect
The vampire no longer requires food or sleep. The Feed ability acts as a long rest without regaining maximum hit points.

Blood Thirst
The vampire needs to feed every 24 hours. If they don't, they begin to suffer the effects of increased hunger. Furthermore, they must roll a d4 every time a humanoid, friend or foe, takes piercing or slashing damage within 30 feet of the vampire. The level of hunger determines the detrimental effects and the chance of feeding, based on the table below:
Level 1 Hunger (after 24 hours): On a roll of 1, the vampire spends their next action to feed on the humanoid. In addition, the Feed ability damage is increased to 4d8 and the vampire has disadvantage on perception checks based on sight.
Level 2 Hunger (after 48 hours): On a roll of 3 or less, the vampire spends their next action to feed on the humanoid. In addition, the Feed ability damage is increased to 6d8, the vampire has disadvantage on all perception checks, and has disadvantage on all Constitution saving throws.
Level 3 Hunger (anytime after 72 hours):  The vampire spends their next action to feed on the humanoid. In addition, the Feed ability damage is increased to 8d8, the vampire has disadvantage on all Constitution saving throws, suffers one point of exhaustion, is unable to regenerate, and cannot use the Vampiric Rage ability.

Vampiric Transformation

3rd Level Vampire Abilities

Increased Movement Speed

Movement speed is increased by 10 upon becoming a vampire.

Claws

The vampire's main attack weapon is replaced by claw attacks. Claws can grow at a moment’s notice, dealing 1D6 + STR modifier. This increases to 1D8 at level 7, 1D10 at level 10, and 1D12 at level 15. In addition, the vampire is also granted the Two-Weapon Fighting style if it is not present already.

Feed

The vampire must feed upon the blood of others to remain strong. When this ability is used, the vampire attempts to latch onto and sink their fangs into the target. Make an attack roll against the target. If the attack hits, the target must make a Constitution saving throw versus a DC 16. On a failed save, the target takes 3d8 + STR worth of necrotic damage and the vampire is healed for the damage dealt. On a successful save, only half the damage is taken and healed. If the target is unconscious, no attack roll is needed and the Constitution save automatically fails. This ability has no effect to the target or the vampire if the target is not a humanoid or is immune to necrotic damage. If the vampire successfully feeds, the Hunger Level is reset and a long rest is taken, however the hit points are not reset to maximum.

Regeneration

Upon becoming a vampire, the body is able to heal itself over time. Each round at the start of their turn, the vampire gains hit points equal to their proficiency bonus. This ability is inactive if the vampire is currently affected by Level 3 Hunger, or if the vampire is unconscious. While unconscious, the vampire may only be healed by blood. If an ally sacrifices a number of hit points in the form of blood, the vampire is healed by the same amount and is restored to consciousness.

Vampiric Senses

7th Level Vampire Abilities

Echolocation

The vampire's senses have been honed to a fine point over time. The vampire now has blindsight up to 120 feet and has advantage on all perception checks based on sound.

Vampiric Grace

With heightened senses and increased mobility, the vampire now has advantage on all athletic and acrobatic checks.

Vampiric Form

10th Level Vampire Abilities

Swarm of Bats

For 1 minute, the vampire may use a bonus action to transform to and from a swarm of bats. While in bat form, the vampire has a fly speed of 30 feet and their AC increases by 3. The swarm may move through an opening large enough for a single bat. This ability may be used once per feeding.

Mist Form

As an action, the vampire is able to transform into a dense cloud of mist that radiates outward in a 20 foot radius. While in this form, the vampire cannot attack, speak, or perform any other actions aside from moving or hovering. The form itself is immune to all non-magical attacks and any allies within the mist have advantage on stealth rolls. Additionally, any ranged attacks made against allies within the mist are made at disadvantage. The form lasts for 1 minute and can be dismissed early if the character chooses. This ability is treated as a concentration spell and can be used once per feeding. 

Vampiric Drain

15th Level Vampire Abilities

Bloodlust

The vampire's taste for blood has become insatiable. If the vampire is currently being affected by Level 2 or higher of the Blood Thirst feature, the vampire can attempt to drain a target by making a melee bite attack against them as an action. On a successful hit, the target must make a Constitution saving throw. On a failed save, the vampire deals 10d8 worth of necrotic damage to the target and is healed for the same amount. Furthermore, the target is restrained for 1 round. If the target succeeds on their save, only half the damage is taken and healed and the target is not restrained. If this attack successfully hits, the vampire takes a long rest, but does not reset their hit points to maximum. Once attempted, this ability cannot be used again until the next time the vampire suffers from Level 2 hunger or higher.

Sacrificial Blood

With this ability, the vampire is able to revive an unconscious target through the sacrifice of blood. The vampire rolls 1d10 and loses hit points equal to the number rolled and immediately gains one level of hunger. The target gains these hit points and is no longer unconscious, after which they must roll a d100. On a roll of 5 or less, the target becomes a vampire themselves and begins multiclassing as a vampire at level 1. This ability may be used once per feeding. If it is used while the vampire is already at level 3 hunger, the vampire suffers another point of exhaustion.

Vampiric Rage

The vampire allows the blood of others to briefly surge through their body, greatly increasing their abilities. The vampire’s Strength and Dexterity are both increased by 3 and the vampire’s movement speed is increased by 10. This effect is activated as a bonus action and lasts for a period of 1 minute. Activating this ability immediately increases the vampire’s hunger by 1 level. This ability may be used as long as the vampire is not currently being affected by Level 3 hunger and all uses are reset after feeding.

Vampire Lord

18th Level Vampire Abilities

Vampiric Flight
The vampire no longer requires being in their bat form to fly and now has a permanent fly speed equal to their walking speed.

Vampiric Seduction
Through sheer will, the vampire attempts to seduce and control a creature as an action. The target must make a Wisdom saving throw against a DC 16. On a failed save, the target is charmed for 1 hour. This ability is treated as a concentration spell and any damage the target takes results in a new saving throw to end the effect. This ability may be used once per feeding.