The principle is using, perhaps balanced with dark, perhaps not, to 'cast' the shows bound to a person outward, weaken its bond with the person and ability to help them, and then try to sever the bond between the stretched out shadow and the person, trapping the shadow in turn.
A normal light source casts a shadow, with a stronger light casting a stronger shadow. Our hope is that a magical light source, one strong enough to hurt an unbound shadow can cast them strongly enough from those they are bound to, to have a few effects:
- Drive much of the shadow out from the body of those they are bound to.
- 'Stretch' the bond between the shadow and those they are bound to, hopefully making it easier to break.
- Pin the shadow, behind the bound person, to protect it from the light (just like a normal shadow)
- Reduce its ability to aid its bound person, due to being cast out and pinned.
This has been the core of my search for a light source, which led to the diaspore. However, the diaspore being the heart of the keep's golem, may be more than just that. It is still unclear.
In addition, there must be some what of dealing with the shadows. While a strong direct light can possibly just destroy unbound ones, or ones whose bond is severed, it is unclear. Thus we wish to have a trap available to deal with the shadows.
The trap that has been considered is a mirror enchanted in its creation by yourself, Initiate Nixa, as binding creatures seems to be something well suited to the sorcerous arts.
A possible construction of the mirror might be a polished silver mirror with an amber frame. However, silver seems to be more harmful to the shadows. Amber itself seems to be more useful as a binding element, as can be seen in its nature holding creatures within it. Thus perhaps, a thin pane of light amber instead of glass, set over a silver mirror frame, and enchanted in its construction to trap the shadows behind the amber.
Plan in action:
There are various ways to put the plan in action, depending on whether the victims are willing or not, aggressive or not.
Take Shadust as the extreme case. Begin a fight, and take out the light source to 'cast' out his shadow and prevent him from using its abilities, including fleeing. Fight him, probably using a silver blade. If possible, kill him, while the person with the trap gets into position by the shadow itself. Use the silver blade to sever the stretched bond between shadow and bound person (there is also some theory that at the moment of death, the bond may be weakened further). Then use the light to drive the shadow into the trap.
For less significantly tainted, including those in the Gaol. Use the light, and the trap and perhaps a blade to sever the bond while they are restrained.
For unbound shadows, use the light to drive the shadows into a corner or behind a protective barrier to pin them and let them be trapped, or if need be. Try to destroy them with unobstructed light.
The plan requires at least two, one to use the light, one to use the trap. If fighting is required, it can be done by the one holding the light, or a third party. Severing the bond could be done by either of the bearers, or a third party.