Re: Champions Assemble!
The characters are students at a School For Gifted Students. They all wear what look like class rings, with the stone a default green.
The rings are multipurpose: they are communicators, they are alert signals, and they are tracking beacon.
When a character sends an alert, it is one of three levels. The stone changes color for each level.
GREEN: The stone lights up (dimly) and emits a mild vibration. Green level means, I've got a problem, and if anyone isn't too busy with something else, please join me.
YELLOW: The stone changes to dimly glowing yellow, also vibrates, slightly stronger. Yellow means, I've got a pretty big problem, please drop anything not absolutely important and get to me asap.
RED: Changes to glowing red, vibrates strongest yet. Red means, all available team members, drop whatever you're doing and get your butts here yesterday, loaded for bear.
The rings can home in on each other (a DETECT), and as previously stated, are also communicators.
Gary