Holy Oil

Holy Oil is a rare substance. Castiel obtains some from Jerusalem, in order to use it to restrain Raphael. When the oil is ignited, its flames will trap Angels and Archangels.

Sam describes it as like "a devil's trap for angels" but it differs because they can still use their powers while trapped within the flames.

References

Castiel and Dean trap archangel Raphael inside a ring of burning holy oil, interrogating him for God's location. He responds, and claims that God is dead. They leave him in the still burning circle.5.03 Free To Be You And Me	Sam and Dean use it to trap the Trickster, forcing him to reveal that he is actually the Archangel Gabriel. Dean releases him by turning on the fire sprinklers	Lucifer uses it to trap Castiel, but he manages to break the circle and escape by throwing Meg on the flames. The extent of her injuries were unclear, but she survives
Castiel uses a molotov cocktail of Holy Oil to momentarily banish Michael	Dean traps the angel Balthazar in a circle of ignited Holy Oil and forces him to return the soul he got from a boy, Aaron Birch, in exchange for a piece of the Staff of Moses. Castiel causes the circle to vanish with a gesture when he wishes to free the angel	Dean, Sam and Bobby trap Castiel in a circle of ignited Holy Oil and forcing him to reveal his secret about working with Crowley. Castiel tells Dean, Sam and Bobby to leave him when the sound of a storm of Demons are coming. In the end its just the arrival of Crowley who causes the circle to vanish with a gesture when he wishes to free the angel .