When you drop to 0 health outside your resting place, you transform into a cloud of mist (as in the Shapechanger trait) instead of falling unconscious, provided that you aren’t in sunlight or running water. If you can’t transform, you are destroyed.

While in mist form, the following rules apply:

• you have health equal to half your normal form’s health
• your only method of movement is a flying speed of 5 meters (hover)
• you can enter and occupy the space of another creature
• you have resistance to nonmagical damage except the damage you take from sunlight and are immune to the exhausted, grappled, paralyzed, petrified, poisoned, prone, and restrained conditions
• you have advantage on Reflex and Fortitude saving throws
• you can move through a space as narrow as 2 centimeters wide without squeezing, though treat liquids as though they were solid surfaces.
• you can’t fall and remain hovering in the air even when stunned or otherwise incapacitated.
• you can’t talk, manipulate objects, attack, use maneuvers, or cast spells. Any objects you were carrying or holding can’t be dropped, used, or otherwise interacted with.
• if you are burning, the condition ends.
• the only actions you can take in this form are the Dash action or to revert to your true form which you can only do if you have more health than half your normal form’s health.

While in mist form, you must reach your resting place within 2 hours or be destroyed. Once in your resting place, you revert to your true form. You are then paralyzed until you regain at least 1 health. After spending 1 hour in your resting place with 0 health, you regains 1 health.