Magic Objects in Rapture

Calling Stones

Calling Stones are enchanted rocks used to communicate over long distances. When activated, any person will be able to activate the spell to "call" another person's stone. The "call" is similar to a video call; an illusion rimmed by pale blue mist will appear above the stone like a reflection in water, and show each user the person on the other side. Others around them will be able to hear both sides.
The length of the "call" is dependent on the intensity of the spell cast upon the stone. Most users use a weak spell that will last, at most, ten minutes, since the spell is only good for a single use. The stones can be "recharged" with a new spell.
Any dark, smooth stone can be turned into a Calling Stone. 

Christ's Ladder (Centaury)

Centaury is an inherently magical plant. Rather contradictory, this plant is an anti-magic plant. If ground into a powder or pulp, it becomes a poison for Supernaturals, especially those whose bodies are created through magic. The poison can be delivered through ingestion(eating) or injection. The plant burns away magic, though it can be worked through a person's system over time.

If the Supernatural is simply somebody who uses magic - for example, a magic-using human - they will simply become very ill and be unable to use their powers. It leaves the victim weak, fatigued, and a little warm. The poison may work its way through the user's system within five days. If the victim's magic doesn't return after five days, they will need another magic user of the same type to reawaken their powers.
If the Supernatural is a being composed of magic, the effect will be much more severe. The victim will develop a high fever, faint, and be in pain. They will be very weak as their body resists the anti-magic properties, and they need to have their very blood "purified" according to their magical alignment. These victims need to be treated within an hour and a half, or they will die.