Angel Banishing Sigil
The Angel Banishing Sigil must be drawn in blood. It temporarily banishes angels (except the one who drew it) from that location. However, in 5.18 Point of No Return, Castiel banishes four angels and himself with a sigil on his chest. Apparently it banishes the angels in range to another location on Earth as after being banished in 7.21 Reading Is Fundamental, he calls from a dog track in Perth, Australia and wound up on a fishing boat after banishing himself and the other angels.
See Enochian for sigils that will prevent an angel entering a building.
When Sam and Dean join Ruby who has hidden Anna Milton from Alastair, Castiel and Uriel appear and proclaim they must kill Anna. As the angels attack, Anna cuts herself and draws the sigil, sending the angels away.
After Castiel found out about Zachariah's true plan he wanted to warn Dean and Sam, but he was ambushed by some of his superiors. Castiel engaged in an angel on angel battle with some of his superiors.
After this angelic battle, Castiel was taken up to Heaven for re-education on angelic obedience. Sam and Dean find the sigil in the place where they were to meet Cas; he presumably used it to try and fight off his captors.
Sam uses a sigil to banish Anna during their first confrontation in 1978. Later, Dean shows John how to make the sigil, but when Anna and Uriel arrive, they somehow defuse the sigil.
Dean uses a sigil to banish Castiel to escape from Bobby's Panic Room. Later, while fighting four angels in the abandoned muffler factory, Castiel takes off his shirt to reveal the sigil carved into his chest with a box cutter. He puts his hand on it and banishes the other angels and himself, giving Sam and Dean an opening to go to the Green Room.
Outside of Balthazar's house, Dean and Sam are confronted by a hostile angel. He is a soldier of Raphael and, rather than fight him with the Angel Killing Swords they have in their possession, Dean banishes him with a Sigil etched on a wall of Balthazar's house.
Samuel draws a modified version of the sigil and activates it, banishing Castiel temporarily.
After Hester and Inias arrive and threaten, Sam, Meg, Kevin Tran and Castiel, Dean uses the sigil to banish all three angels. While it is unknown where the other two angels went, Castiel ends up at a dog track in Perth, Australia.