Shapechanger (Mist Form)

Vampires are known for their ability to shift from form to form. You gain the shapechanger tag and if you are not in sunlight or running water, you can use your action to polymorph into a Medium cloud of mist for 1 minute, or back into your true form.

Mist Form: While in mist form, you can't take any actions, speak, or manipulate objects. You are weightless and have 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. You have advantage on Strength, Dexterity, and Constitution saving throws, gain a number of temporary hit points equal to twice your level, and are immune to all non-magical damage, except the damage you take from sunlight.

Level 15 -  You gain humanoid form. You can use your action to polymorph into a Small or Medium humanoid you have seen, or back into your true form. Your statistics, other than your size, are the same in each form. Any equipment you are wearing or carrying isn't transformed and you revert to your true form if you die. While in this form you can use your Bite and Claws attacks.

Once you transform this way you cannot do so again until you complete a short or long rest.