As Shadowsight stared at him with a mixture of fear and disbelief, he thought he saw the edges of Bramblestar’s body begin to blur, as though mist were seeping out of his pelt. A heartbeat later another cat slid out like smoke from a burning fire and stood in front of Shadowsight, while the body he had left slumped to the floor of the den.
A glow pulsed around the cat’s pelt; Shadowsight found it hard to make out  the  color  of  his  fur.

Veil of Shadows, Chapter 13