Vampirism Player Rules

(note: these are extremely close to the rules found in the monster manual starting p. 295)

Basic changes

• Base stats for STR/DEX/CON become 18.  Treat this as a magical effect and note down the old base stats somewhere in case of a cure later.
• gain Damage resistance vs. necrotic and nonmagical bludgeoning/piercing/slashing attacks.
• gain 120ft. darkvision.
• You must rest in your coffin to gain any benefit.  That coffin can be mobile.  If destroyed, a four hour ritual can be performed to "bind" you to a new coffin.  Suffer a level of exhaustion for each night without rest as per normal rules
• You must drink blood instead of normal food.  Suffer from starvation following the normal 5e starvation rules.
• You can't enter a residence without an invitation from one of the occupants.
• You can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
• You take 20 acid damage if you end your turn in running water
• If a piercing weapon made of wood is driven into your vampire's heart while you are incapacitated in your coffin, you are paralyzed until the stake is removed.
• You take 20 radiant damage when you start your turn in sunlight.  While in sunlight, you have disadvantage on attack rolls and ability checks

New traits

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, the vampire 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.

Misty Escape

When it drops to 0 hit points outside its resting place, the vampire 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

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

New Attacks

• If in your vampire form, you may attack twice in a single action. 
• Unarmed strikes deal 1d8+str mod bludgeoning damage.  On a hit, you may choose to automatically grapple the target instead of dealing damage

Bite (Bat or Vampire Form Only)

Melee Weapon attack (str-based, proficient), one willing creature, or a creature that is grappled by you, or which is incapacitated, or restrained. deals 1d6 + str mod piercing damage plus 3d6 necrotic damage. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and you regain hit points equal to that amount. The HP 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 your control.

Vampire Charm

Targets one humanoid you can see within 30 feet of you.  If the target can see you, they must succeed on a Wisdom saving throw (DC 8 + proficiency + charisma mod) against this magic or be charmed.  The charmed target regards you as a trusted friend to be heeded and protected. Although the target isn't under your control, it takes your requests or actions in the most favorable way it can, and it is a willing target for your vampire's bite attack.
Each time you or your 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 you are destroyed, on a different plane of existence than the target, or take a bonus action to end the effect.