In order for a shadow to exist there must be some light. Without "light" there is no shadow .Shadows are the result of light.Shadows hide in dark corners but they can't exist without light. We don;t want to kill the shadow .So ...to trap the runaway shadow. How do we do that? First of all Phantasm must be alone , so the shadow won't have anyone else to possess, second he should be alone in a room/place/cave where the shadow can't hide, a room/place/cave so lighten that the shadows only option should be bonding back with phantasm. The normal reaction of the shadow would be to hide from the "light" that gave him life. Hide ..but where?*grins* well the only place left to hide would be Phantasm dark piece of soul( where feelings anger, rage, frustration and desperation are).The Shadow will be drawn to that. We all have that. Some of us show it some of us keep it well hidden, some of us don't even realize having it. What do we need ? Torches to light up each corner of the room /place where the "entrapment" will take place . A knife ( Just a simple knife .No powers needed) Phantasm must do a sacrifice. The knife will be used by himself to open his dark side of the soul but only with his mind , no blood will be spilled, only the soul will be opened. After the shadow reacts and hides in the only place left with the hope of regaining it;s powers by feeding on Phantasm's dark feelings, comes the tricky part. Keeping it there. A ring should help us. A ring that will help Phantasm concentrate his dark feelings and draws them like a magnet. As long as Phantasm wears the ring the shadow will feast on the dark feelings trapped in it but wont gain enough power to escape again.