Sanguinastone

Sanguinastones are a special dark magical substance made from different ingredients.

Use
Sanguinastones trap those inside the in an unconscious state. It then proceeds to slowly suck their life out. When the stone is clear, the person inside is dead.

Users
Angeline used this to trap Nessa's real body so that her clone could take her place. In the end, strangely, she didn't kill Nessa, saving her instead, as if she was just "playing."

Trivia

 * "Sanguine" means bloody, and the word is used as a prefix for the stone's name