I use the following, with each type of lycanthrope being its own class progression. Basically, rather than getting immunity, I increase their Hit Dice per the DMG guidelines and give them silver vulnerability (in the case of lycanthropes). The justification as to why the curse is different for them than for NPCs is because, rather than letting the curse master them (which would cause them to become an evil NPC), they are attempting to master the curse.
Edit: I should note that these are bigger Hit Dice, not more. A 4d8 HD only gains the Constitution modifier once.
Lycanthropes
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Prerequisite: You must be of humanoid type and have contracted the appropriate form of lycanthropy
Cursed lycanthropes are rare individuals who’ve contracted lycanthropy but possess the will to fight to master the curse rather than allowing the curse to master them. If you ever willingly embrace the curse, you become a full powered lycanthrope immediately, as per the Monster Manual, but you also become an NPC until cured.
Upon contracting lycanthropy, you become a level 0 lycanthrope of the appropriate type. You may choose to freely take levels in your lycanthrope class, or not, as you see fit. Once you gain your first level in your lycanthrope class, your lycanthropy can only be cured if you are willing to allow it. However, if your lycanthropy is cured, you lose all of your lycanthrope class levels and revert to an experience total equal to what will get you halfway through your new level. Should you ever become a lycanthrope again (even if not of the same type), you regain the lost XP and it is applied towards levels in your Were-class. Note that if you gained experience in the meantime, this may mean your Were-class level is lower than it was prior to being cured. This XP can ONLY be applied to your Were-class.
Bob the second level Fighter is bitten by a werewolf and contracts lycanthropy. He adventures for a bit and becomes a Fighter 3 / Werewolf 2 with 6,500 XP. Tired of chasing postal workers during the full moon, he elects to be cured. He becomes a third level Fighter with 1,800 XP, the midpoint between levels 3 and 4. Should he ever contract lycanthropy again, he immediately gains 4,700 XP, which is applied to levels (if any) in his Were-class.
(Bob the third level Fighter contracts lycantropy and gains two levels of Werewolf. Tired of chasing postal workers during the full moon, he elects to be cured. He reverts to a third level character with 1,800 XP, the midpoint between levels 3 and 4.)
Moon Rage
Until you fully master your curse, you suffer Moon Rage. When angered, particularly during a full moon, you risk losing control of yourself. If significantly angered, you must make a Wis save against a DC of 5. If a hostile creature damages you, the DC equals half the damage dealt. During the full moon the save is made with disadvantage, while conversely during the new moon you have advantage.
If you fail the save you transform into your hybrid form and go berserk. While berserk, you must use your action each round to attack the nearest creature with your hybrid form’s natural attacks. (If multiple creatures are the nearest, the target is determined randomly.) If you drop your target, you move on to the next nearest creature and attack them. You continue to berserk until you start your turn with no creatures within 60 ft of you that you can see or hear.
When Moon Rage ends, you may choose to remain in Hybrid form or use an action to revert to your humanoid form (or assume animal form, if you’ve attained that ability). However, until you gain the ability to assume Hybrid form at will, you have disadvantage against saves to resist entering Moon Rage while in Hybrid form (you do NOT suffer the same penalty when saving to exit Moon Rage).
Werewolf
Starting Features
Shapechanger: You gain the shapechanger subtype.
Keen Senses: You gain Perception as a skill (double proficiency bonus), and have advantage on Perception checks that rely on hearing or smell.
Moon Rage: You suffer from Moon Rage.
Silver Vulnerability: You have vulnerability to silver.
Stealthy: You gain Stealth as a skill.
Control: The bonuses listed are added to saves made against Moon Rage.
Penetration: You natural attacks treat immunity to silver or non-magical weapons as resistance, and ignore these types of resistance.
Leveling
Bite (Wolf or Hybrid form only): 1d8 + Str OR Dex piercing dmg. If the target is humanoid, it must make a Con save DC 8 + proficiency + Con or be cursed with werewolf lycanthropy.
Claws (Wolf or Hybrid form only): 2d4 + Str OR Dex slashing dmg.
Wolf Form: You can use your action to polymorph into a Wolf, or back into your humanoid form. Your statistics, other than natural armor and speed, are the same as your humanoid form. Any equipment you are wearing or carrying isn’t transformed. You revert to your humanoid form if you die. You cannot speak in wolf form.
Speed: 40
Light Natural Armor 12 + Dex mod
Non-Biped – Non humanoids do not have hands and must typically use their mouths to manipulate objects. Therefore they have disadvantage when using tools and cannot use all equipment (case by case basis). Any monster, if proficient, can wield a weapon in its mouth. If you have one head you can two hand a weapon. If you have two heads you can dual wield but cannot two hand (because your other head(s) get in the way).
Impassioned Plea: If you are under the effects of Moon Rage and an adjacent creature uses its action to plead with you, you can make an immediate DC 17 save to end Moon Rage.
Extra Attack: In your humanoid form, you can make two weapon attacks as an action.
Sated Bloodlust: If you are under the effects of Moon Rage and you drop a creature to 0 HP, you may make an immediate DC 15 save to end Moon Rage.
Hybrid Form: You can use your action to polymorph into a wolf-humanoid hybrid, or back into your humanoid form. Your statistics are the same as your humanoid form. Any equipment you are wearing or carrying isn’t transformed. You revert to your humanoid form if you die.
As an action, can make one Bite attack, and one attack with Claws or a weapon.
Light Natural Armor 12 + Dex mod
Mastery: You can assume Hybrid or Wolf form, or revert to your humanoid form, as a bonus action.
Total Control: You no longer suffer from Moon Rage.
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Vampires
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Prerequisite: You must be of humanoid type, and be killed by the bite of a master vampire and then buried
Cursed vampires are rare individuals who rise from the grave as vampire spawn but do not allow the curse to take them. They struggle to restrain their unquenchable thirst for blood, fighting against the dark impulses that course through their cold veins. If you ever willingly give in to the curse, you become a full powered vampire spawn immediately, as per the Monster Manual, but you also become an NPC unless you are somehow cured of your vampirism.
Upon rising as a vampire, you become a level 0 vampire. You may choose to freely take levels in the cursed vampire class, or not, as you see fit. If your vampirism is ever cured, you lose all of your vampire class levels and revert to an experience total at the midpoint of your new character level. Should you ever become a vampire again, you regain the lost XP and it is applied towards levels of Cursed Vampire. Note that if you gained experience in the meantime, this may mean your Vampire level is lower than it was prior to being cured. This XP can ONLY be applied to your Vampire class.
Bob the second level Fighter is slain be a master vampire and rises as a vampire. He adventures for a bit and becomes a Fighter 3 / Vampire 2 with 6,500 XP. Tiring of never seeing the sun, his companion slay him and raise him from the dead. He becomes a third level Fighter with 1,800 XP, the midpoint between levels 3 and 4. Should he ever become a Vampire again, he immediately gains 4,700 XP, which is applied to levels (if any) in Vampire.
Starting Features
Undeath: Your type changes to Undead.
As an undead creature, you are unable to benefit from most healing magic.
Blood Frenzy: Until you fully master your curse, you suffer Blood Frenzy. When you scent blood, particularly if you haven’t fed recently, you risk losing control of yourself. If a living creature with blood within 60 ft of you is reduced to 1/2 HP (bloodied), you must make a DC 5 Wis save or enter blood frenzy. If the creature is reduced to 0 HP (dying), you must make a DC 15 Wis save. For each day you have gone without feeding on the blood of a living creature, you get a cumulative – 1 penalty on saves to resist entering Blood Frenzy. If you go a week without feeding on the blood of a living humanoid, you have disadvantage on saves to resist entering Blood Frenzy. Conversely, if you have fed on the blood of a living humanoid within the past day, you have advantage to resist entering Blood Frenzy.
If you fail the save you frenzy. While frenzied, you must use your action each round to attack the nearest bloodied or dying creature with your Claws and/or Bite until it is dead. (If multiple viable creatures are the nearest, the target is determined randomly.) If you kill your target, you move on to the next nearest viable creature and attack them. If there are no bloodied or dying creatures, you attack the nearest living creature with blood. You continue to frenzy until you start your turn with no living creatures with blood within 60 ft of you that you can see or hear.
Thrall: The blood of the master vampire who sired you pulses through your veins, and gives him power over you. If he gives you a command (free action, but no more than once per round), you must make a DC 10 Wis save to resist, or you comply. If the command is an ongoing one, you may repeat the save at the end of each of your turns. In order to harm him directly, you must make a DC 20 Wis save or you must choose a new target for the spell or attack. If you cannot, your action is wasted. This applies to area effects as well as targeted attacks. Direct harm includes damaging effects as well as effects that would hinder him, but does not include harming his minions or stealing from him.
Vampiric Weaknesses
Forbiddance: You cannot enter a residence without an invitation from one of the occupants.
Harmed By Running Water: You take 20 acid damage if you end your turn in running water.
Stake to the Heart: You are destroyed if a piercing weapon made of wood is driven into your heart while you are incapacitated.
Sunlight Hypersensitivity: You take 20 radiant damage if you start your turn in sunlight. While in sunlight, you have disadvantage on attack rolls and ability checks.
Penetration: You natural attacks treat immunity to non-magical weapons as resistance, and ignore this type of resistance.
Bite (can only be used on a willing, grappled, incapacitated, or restrained creature): 1d6 + Str OR Dex piercing dmg plus 2d6 necrotic dmg. The target’s max HP is reduced by an amount equal to the necrotic dmg taken, and you regain HP equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if its max HP is reduced to 0. This counts as feeding.
Enhanced Senses: You gain Perception as a skill, and Darkvision 60.
Control: The bonuses listed are added to saves made against Blood Frenzy and Thrall.
Leveling
Claws: 2d4 + Str OR Dex slashing dmg. Instead of dealing dmg, your can grapple the target (escape DC 10 + Str).
Stealthy: You gain the Stealth skill.
Tough: You have light natural armor 12 + Dex mod
Slaked Thirst: If you are under the effects of Blood Frenzy and you successfully damage a living creature that has blood with your Bite, you may make an immediate DC 15 save to end Blood Frenzy.
Nightsoul: You gain resistance to necrotic damage.
Impassioned Plea: If you are under the effects of Blood Frenzy and an adjacent creature uses its action to plead with you, you can make an immediate DC 17 save to end Blood Frenzy.
Multiattack: You may make two attacks as an action, only one of which may be a Bite.
Memories of Life: If you are under the effects of Blood Frenzy, and are targeting an ally, before making your first attack you may make an immediate DC 15 save to end Blood Frenzy, but you lose your action if successful.
Spider Climb: You can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Flickering Awareness: While under the effects of Blood Frenzy, at the end of each of your turns, you may make a DC 17 save to end Blood Frenzy.
Regeneration: You regain 10 HP at the start of your turn if you have at least 1 HP and you aren’t in sunlight or running water. If you take radiant damage or damage from holy water, this doesn’t function on your next turn.
Mastery: You take half damage from sunlight and running water.
Total Control: So long as you feed once a month, you no longer suffer Blood Frenzy. Additionally, your sire has no power over you (you are no longer under the effects of Thrall).
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