Watcher's HornLevel 9 Common

This small black horn produces no noise when sounded, but it awakens your slumbering friends and makes them ready to fight.

Wondrous Item        4,200 gp

Power ✦ Daily (Minor Action)

The horn silently awakens each sleeping ally within 10 squares of you. Each ally is not surprised when he or she wakes up.

Published in Player's Handbook 2, page(s) 211.