True Vampirism is imparted on a person not by disease or infection from the body or magic of another vampire, but purely through the draining of one's blood. A simple, single bite is not enough. It is a ritual. While there are a few methods of this ritual, all of them require bringing the victim as near to death as they can get and then imparting vampiric blood upon them.
The most common ritual in turning a vampire is through another vampire's bite. A vampire must drain enough blood to bring a victim to the brink of death. When done right, this will send the victim into a pseudo-coma state and shall remain unconscious for 3 days. At the end of the 3 days, the vampire must be near enough to the victim to impart upon them a taste of their own blood. If the vampire is absent, it is up to the victim's will, constitution, and perhaps the aid of others, to survive. Otherwise, they will simply die.
After tasting the blood of their vampire sire, the victim will awake as a vampire the next day. In the first few days of their new lives as a Vampire, their hunger will be insatiable. This is another reason for their vampire sire to be near, lest they go off in a chaotic rage to get any and as much blood as they can. Typically, this is done in the same fashion in which they were turned. Often, these newly-sired vampires who lack their sire's guidance, wind up truly dead after a short while, since their rampant activity will bring every nearby vampire hunter to them.
Once turned, and in control of their new-born hunger, a Vampire is something more. They have gained the following traits:
- 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. 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.
- Sunlight Sensitivity: While in sunlight, the vampire has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
- Forbiddance: The vampire can't enter a residence without an invitation from one of the occupants.
- Stake to the Heart: If a piercing weapon made of wood is successfully driven into the vampire’s heart, the vampire is considered paralyzed until the stake is removed.
- Bite: The vampire gains a natural weapon called "Bite." With their Bite, a vampire deals 1d4 + STR necrotic damage. A target must be grappled to be attacked with a Bite. On a hit, the target's HP Maximum is reduced by the damage amount and the vampire regains as many hit points. The HP max reduction persists until a long rest is taken. If damage from a Bite brings a target to 0 HP, they die. A humanoid brought to 0 HP in this way can be buried and rise 3 days later as a Vampire.
- Misty Escape: When it drops to 0 hit points, the vampire transforms into a cloud of mist (as in the Shapechanger trait) instead of falling unconscious, provided that it isn’t in sunlight. If it is dropped to 0 hit points by radiant damage, this effect does not trigger, and the vampire is, instead, destroyed. If it can’t transform, it is, instead, 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. The rest of its hit points are regained over a period of 1d4 hours. - While a True Vampire, you have resistance to Bludgeoning, Piercing, and Slashing from Nonmagical Attacks, immunity to cold & necrotic damage, and are vulnerable to fire damage.
- Charm: The vampire targets one humanoid it can see within 30 feet of it. If
the target can see the vampire's eyes, the target must succeed on a DC 17
Wisdom saving throw against this magic or be charmed by the vampire. The charmed target regards the vampire as a trusted friend to be heeded and
protected. Although the target isn’t under the vampire’s control, it
takes the vampire’s requests or actions in the most favorable way it
can, and it is a willing target for the vampire’s bite attack.This also makes available further effects the vampire may have.
Each time the vampire or the vampire’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 the vampire is destroyed, is on a different plane of existence than the target, or takes a bonus action to end the effect. - Legendary Resistance (1/Day): If the vampire fails a saving throw, it can choose to succeed instead.
Regardless of your class, as a Vampire you know the spell Blood Drain. You can cast it, four times per day, as a 1st Level spell, without using material components or a spell slot. All damage dealt by casting the spell in this way restores your own HP by the same amount.