Homebrew, Monster Manual (5e)
Shapechanger. If Lady Adeline isn't in sunlight or running water, she can use its action to polymorph into a Tiny bat or a Medium cloud of mist, or back into her true form.
While in bat form, Lady Adeline can't speak, her walking speed is 5', & she has a flying speed of 30'. her statistics, other than her size & speed, are unchanged. Anything she is wearing transforms with her, but nothing she is carrying does. She reverts to her true form if she dies.
While in mist form, Lady Adeline can't take any actions, speak, or manipulate objects. She is weightless, has a flying speed of 20', can hover, & can enter a hostile creature's space & stop there. In addition, if air can pass through a space, the mist can do so without squeezing, & she can't pass through water. She has advantage on Strength, Dexterity, & Constitution saving throws, & she is immune to all nonmagical damage, except the damage she takes from sunlight.Fey Ancestry. The vampire has advantage on saving throws against being charmed, & magic can't put her to sleep.
Legendary Resistance (3/Day). If Lady Adeline fails a saving throw, she can choose to succeed instead.
Misty Escape. When she drops to 0 hit points outside her resting place, Lady Adeline transforms into a cloud of mist (as in the Shapechanger trait) instead of falling unconscious, provided that she isn't in sunlight or running water. If she can't transform, she is destroyed.
While she has 0 hit points in mist form, she can't revert to her vampire form, & she must reach her resting place within 2 hours or be destroyed. Once in her resting place, she reverts to her vampire form. She is then paralyzed until she regains at least 1 hit point. After spending 1 hour in her resting place with 0 hit points, she regains 1 hit point.
Regeneration. Lady Adeline regains 20 hit points at the start of her turn if she has at least 1 hit point & isn't in sunlight or running water. If Lady Adeline takes radiant damage or damage from holy water, this trait doesn't function at the start of the vampire's next turn.
Spider Climb. Lady Adeline can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Vampire Weaknesses. Lady Adeline has the following flaws:
Multiattack (Vampire Form Only). Lady Adeline makes two attacks, only one of which can be a bite attack.
Unarmed Strike (Vampire Form Only). Melee Weapon Attack: +8 to hit, reach 5', one creature. Hit: 7 (1d8 + 3) bludgeoning damage. Instead of dealing damage, the vampire can grapple the target (escape DC 17).
Bite (Bat or Vampire Form Only). Melee Weapon Attack: +8 to hit, reach 5', one willing creature, or a creature that is grappled by the vampire, incapacitated, or restrained. Hit: 6 (1d6 + 3) piercing damage plus 10 (3d6) necrotic damage. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and the vampire regains hit points equal to that amount. The 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 the vampire's control.
Charm. Lady Adeline targets one humanoid she can see within 30' of her. If the target can see Lady Adeline, the target must succeed on a DC 16 Wisdom saving throw against this magic or be charmed by Lady Adeline. The charmed target regards Lady Adeline as a trusted friend to be heeded & protected. Although the target isn't under Lady Adeline's control, it takes the vampire's requests or actions in the most favorable way she can, and she is a willing target for the vampire's bite attack.
Each time Lady Adeline or her 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 Lady Adeline is destroyed, is on a different plane of existence than the target, or takes a bonus action to end the effect.
Children of the Night (1/Day). Lady Adeline magically calls 2d4 swarms of bats or rats, provided that the sun isn't up. While outdoors, she can call 3d6 panthers instead. The called creatures arrive in 1d4 rounds, acting as allies of Lady Adeline & obeying her spoken commands. The beasts remain for 1 hour, until she dies, or until she dismisses them as a bonus action.
Lady Adeline can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time & only at the end of another creature's turn. She regains spent legendary actions at the start of her turn.
If the vampire is destroyed, these effects end after 2d6 days.
Forest, Swamp, Urban