Barovia

Shapechanger. If Strahd isn’t in running water or sunlight, he can use his action to polymorph into a Tiny bat, a Medium wolf, or a Medium cloud of mist, or back into his true form. Misty Escape. When he drops to 0 hit points outside his coffin, Strahd transforms into a cloud of mist (as in the Shapechanger trait) instead of falling unconscious, provided that he isn’t in running water or sunlight.