It is inspired by Vampire the masquarade (white wolf or GURPS). I have a list of disciplines if you like the concept. A vampire has a package giving a virtual +4 levels at level 1 (cr 5 monsters instead of cr 1 monsters are an easy fight). Plus the regular race (elf, human, etc).

Vampire Template

• Resistance to nonmagical weapons (bludgeoning, piercing, and slashing damage from nonmagical attacks)
• +20 hit points
• Regeneration: at the start of each of your turns, you regain hit points equal to (5 × proficiency bonus − 1), unless you have taken aggravated damage since the end of your last turn (from magical weapons, radiant damage, or fire damage)
• You do not need to sleep, eat, or drink
• You do not age
• You gain the Undead creature type 
• Vulnerability to sunlight :1 hp/minute/level

Frenzy

When subjected to intense stress, hunger, humiliation, or the scent of fresh blood, the vampire must succeed on a Wisdom saving throw or enter a Frenzy.

Suggested DCs

• Minor stress: DC 10
• Serious injury: DC 15
• Starvation or overwhelming blood exposure: DC 18 or higher

While Frenzied

Benefits

• Advantage on melee attack rolls
• Resistance to being frightened
• Your speed increases by 10 feet

Drawbacks

• You must move toward the nearest perceived prey
• You cannot concentrate on spells
• You have disadvantage on Wisdom ability checks
• You cannot willingly retreat
• If you are able to make an attack, you must do so

Duration

A Frenzy lasts for 1 minute.

Alternatively, the vampire may repeat the saving throw at the end of each of its turns, ending the Frenzy on a success.

Vampire Families

Families do not impose automatic Discipline choices. Discipline selection remains fully customizable.

There are 8 Disciplines with 5 ranks each, and characters gain 2 Discipline ranks per level. By 20th level, a vampire can possess every Discipline ability.

Each family has unique Frenzy triggers and Frenzy behaviors.

(The names from Vampire: The Masquerade are copyrighted and should not be reused directly.)

Clan Celerity (“Blood of Storms”)

Theme

An impossibly fast supernatural predator.

Frenzy Triggers

• Losing initiative
• Being immobilized
• Physical humiliation
• Being restrained or paralyzed

Frenzy Behavior

• Obsessive movement
• Must Dash or attack each turn
• Cannot willingly remain stationary

Clan Dominate (“Throneborn”)

Frenzy Triggers

• Direct disobedience
• Mockery
• Loss of social control

Frenzy Behavior

• Obsession with domination
• Focuses on the source of the insult
• Ignores secondary dangers

Clan Obfuscate (“Veiled Ones”)

Frenzy Triggers

• Public exposure
• Bright light
• Losing stealth

Frenzy Behavior

• Paranoid flight
• Obsession with hiding
• Refuses direct engagement

Clan Protean (“Flesh Eaters”)

Frenzy Triggers

• Smell of blood
• Nearby creatures at low hit points
• Mutilation

Frenzy Behavior

• Forced transformation
• Prioritizes natural weapon attacks
• Cannot use social or control powers

Balanced around regeneration and melee combat.

Clan Majesty (“Kings of Night”)

Frenzy Triggers

• Social humiliation
• Rejection
• Loss of status

Frenzy Behavior

• Emotional domination
• Involuntary fear aura
• Incapable of subtle diplomacy

Excellent thematic identity.

Clan Auspex (“Watchers”)

Frenzy Triggers

• Sensory overload
• Illusions
• Psychic assault

Frenzy Behavior

• Hallucinations
• Disadvantage on concentration checks
• Distorted perception

Balanced by extremely strong detection utility.

Disciplines

Obfuscate

Stealth, infiltration, invisibility.

Celerity

Supernatural speed and temporal acceleration.

Potence

Supernatural physical strength.

Auspex

Heightened supernatural perception.

Animalism

Control over beasts and primal instincts.

Dominate

Mental domination and control.

Majesty

Fear, awe, and social supremacy.

Protean

Monstrous physical transformation.

I think the difference of level is the same level by level, because there is a competition between thse disciplines abiliti4es and a regular class.
Roughly +4. But, of course, classes/archetypes with a lot of passive abilities rock. Like the champion. Usually those that are considered underpowereds.

Simple Conversion Table

For the generation... Il just see 2 feats, giving advantage to saving throws vs disciplines. 2 levels.

2 feats vs 0 means immunity.