Shapechanger. If Anastrasya 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 its true form.

While in bat form, Anastrasya can’t speak, her walking speed is 5 feet, and she has a flying speed of 30 feet. Her statistics, other than its size and speed, are unchanged. Anything she wearing transforms with her, but nothing it is carrying does. It reverts to its true form if it dies.

While in mist form, Anastrasya can’t take any actions, speak, or manipulate objects. She 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.

Legendary Resistance (2/Day). If Anastrasya fails a saving throw, she can choose to succeed instead.

Misty Escape. When she drops to 0 hit points outside her resting place, Anastrasya 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 it can’t transform, it is destroyed.

While it has 0 hit points in mist form, she can’t revert to its vampire form, and it 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. Anastrasya 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 Anastrasya takes radiant damage or damage from holy water, this trait doesn’t function at the start of Anastrasya’s next turn.

Spider Climb. Anastrasya can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Vampire Weaknesses. Anastrasya has the following flaws due to being a Vampire:

Forbiddance. The vampire can’t enter a residence without an invitation from one of the occupants.

Harmed by Running Water. The vampire takes 20 acid damage if it ends its turn in running water.

Stake to the Heart. If a piercing weapon made of wood is driven into the vampire’s heart while the vampire is incapacitated in its resting place, the vampire is paralyzed until the stake is removed.

Sunlight Hypersensitivity. The vampire takes 20 radiant damage when it starts its turn in sunlight. While in sunlight, it has disadvantage on attack rolls and ability checks.

Unarmed Strike (Vampire Form Only). Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 8 (1d8 + 3) bludgeoning damage. Instead of dealing damage, Anastrasya can grapple the target (escape DC 17).

Bite. (Bat or Vampire Form Only). Melee Weapon Attack: +8 to hit, reach 5 ft., one willing creature, or a creature that is grappled by Anastrasya, 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 Anastrasya 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 Strahd's control.

Advanced Combat Charm. Anastrasya targets up to 2 creatures she can see within 60 feet of her who's CR/Level are equal to or lower than half her CR rounded down (7). If the target can see Anastrasya, the target must succeed on a DC 19 Wisdom saving throw against this magic or be charmed by Anastrasya.  The charmed target regards Anastrasya and Strahd von Zarovich as their masters. It will do whatever it can to protect them. The creature gains a +2 bonus to AC, damage, and attack rolls while under the effect of this charm. Anastrasya must concentrate on this Advanced charm as if it were a spell, but can target additional creatures each time she uses this action, with no limit on how many targets she can charm. If her Concentration is broken she loses her charm on all of her targets.

Each time Anastrasya or Anastrasya'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 Anastrasya is destroyed, is on a different plane of existence than the target, or takes a bonus action to end the effect. Once the effect ends, the target is immune to all vampire charm effects for 24 hours.

Charm. Anastrasya targets one humanoid she can see within 30 feet of her. If the target can see Anastrasya, the target must succeed on a DC 19 Wisdom saving throw against this magic or be charmed by Anastrasya. The charmed target regards Anastrasya as a trusted friend to be heeded and protected. Although the target isn’t under Anastrasya's control, it takes the her requests or actions in the most favorable way it can, and it is a willing target for her bite attack.

Each time Anastrasya 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 she is destroyed, is on a different plane of existence than the target, or takes a bonus action to end the effect. Once the effect ends, the target is immune to all vampire charm effects for 24 hours.

Beguiling Command. Anastrasya can command one of her charmed targets to take an Action. That action can be used only to take the Attack (one weapon attack only), Dash, Disengage, Hide, or Use an Object action.

For our Master! When Anastrasia is hit by a weapon attack or spell attack, she can command a charmed creature within 10 ft. of her to jump in the way of the attack and take the damage for her.

Anastrasya can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. Anastrasya regains spent legendary actions at the start of its turn.

Move. Anastrasya moves up to its speed without provoking opportunity attacks.

Unarmed Strike. Anastrasya makes one unarmed strike.

Command Attack (Costs 2 Actions). Anastrasya uses her Beguiling Command ability.