A locating spell. When you witches use crystals and then prisms and mirrors to divine images of who you're trying to find.
Sam and Dean interrogate a witch who survived a demon attack on Rowena in a restaurant. The woman feigns ignorance about being a witch or knowing what scrying is until Sam dumps out her purse and finds chicken bones, hex bags, and a pentagram. She attempts to perform a spell, but it stops. Dean convinces her that if she gives up Rowena, Crowley would no longer want her dead. When she tells the Winchesters she doesn't have her crystals, Dean offers her her cosmetic mirror. After a simple Latin incantation, the witch is able to divine that Rowena is in the middle of packing a bag.
"Ostende mihi illum quem quaero."
After Crowley persuades her to help him get revenge, Rowena casts a scrying spell using a crystal ball to search for Lucifer's aura. After a brief fight, Rowena manages to detect and locate Lucifer. She uses the same Latin incantation from 11.03 The Bad Seed, albeit with two words mixed up:
"Ostende illum mihi quem quaero."
When the Alpha Vampire leads a vampire attack on the British Men of Letters Mobile Command and causes the comms to go out, Serena Colman suggests a scrying spell to get a message to England for help. Sam shoots this down, telling her they can't wait for backup.