A fog cloud can fly/float, and flow under doors. Due to its unusual body chemistry, It has no need to breathe. It has an insubstantial body. It has no eyes, and is therefore impervious to gaze and blindness attacks. A fog cloud has no mind, and is therefore not detectable via telepathy. It has no limbs and no head.

The fog comes
on little cat feet. It sits looking
over harbor and city
on silent haunches
and then moves on.
Fog, by Carl Sandburg