Before introduce that item, think about the game consequences.
That PC always can take advantage of dim light (on born of shadows feat and other). It is like a stone to rogue that grant him combat advantage as minir action.
If that's ok, i have a suggestion to fluf the stone
Enconter power (standard).
The stone releases all the light it drained from the ambient.
Close burst 3 (all creatures)
At vc will or ref
Target is blinded until the end of your next turn
Encounter power (move)
Close burst 3
Extingues all fire from torch and others light source
That PC always can take advantage of dim light (on born of shadows feat and other). It is like a stone to rogue that grant him combat advantage as minir action.
If that's ok, i have a suggestion to fluf the stone
Enconter power (standard).
The stone releases all the light it drained from the ambient.
Close burst 3 (all creatures)
At vc will or ref
Target is blinded until the end of your next turn
Encounter power (move)
Close burst 3
Extingues all fire from torch and others light source