Scrying Crystals

Scrying crystals are used by witches to locate other witches, innocents in danger, and demons.

Innocents Lost
When they learned in No Rest for the Wicca that all of their innocents were in danger, it spured on a search in this issue to locate and protect their past innocents and charges. Piper was using a scrying crystal to try and locate their charges while Paige worked with Henry to look through police files to see if they can find anyone. Once they had found what they could from Henry, Paige returned and they used a scrying crystal to locate Tyler Michaels.

Four's Company
Piper uses the scrying crystal to try and locate Leo while he is being held by Rennek. The first time she tries, like the rest of her powers, it doesn't work properly. It just goes round and round without ever landing anywhere. Presumably once Prue has stripped her powers, restoring Piper and Phoebe's ability to use their powers, Piper once more does some scrying, which is how she is able to locate Leo.