Shadow-Whispering

"It's called shadow-whispering. My shadow is carrying my consciousness so nobody can hear me except you..."
- Tam Song, Book 4: Neverseen 

Shadow-Whispering is a unique skill to Shades that allows them to spread their consciousness via shadows. Like telepathically transmitting, a voice is able to communicate with one or more elves, while silent to those nearby. It is described as sounding like somebody is whispering very close to your ear.