Expelling Angels

Expelling angels is a spell that banishes all celestial beings from Heaven, as well as burn off the wings of the angels already on earth.

Background
This spell was unknown to most angels. The only angel with initial knowledge of this was Metatron, the Scribe of God. Metatron convinced Castiel to perform the spell, under the notion that the spell was the set of trials that would lock the gates of Heaven to solve the problems of the angels. Wanting to atone for his sins and wanting to restore Heaven to its former peaceful state, Castiel agreed to the plan. Naomi caught wind of the spell and its near-completion. However, she was killed by the Scribe before she could properly recruit Castiel to stop the spell from being complete. When Castiel returned to Heaven, Metatron took Castiel's grace, thus completing the spell and banishing all angels save himself from Heaven. All angels, including imprisoned ones such as Gadreel were expelled, but many died in the fall, including Ezekiel, Sophia and Azrael. The ones who survived suffering agonising pain as their wings were burned off their backs as they fell. Many were greatly weakened by its effects. Not only were they cast out of Heaven, but the spell also burned off all their wings, forcing them to manifest as luminous blue smoke, instead of blinding white light. The spell doesn't seem to cut them off from Heaven's power, but only denies them teleportation. This is shown as they can still smite and heal, unlike normal fallen angels. According to Crowley, the Angel Tablet says the spell is irreversible.

Since no angel may enter Heaven, reapers no longer have access to it, so anyone who dies on Earth and is supposed to go to Heaven is now stuck as a ghost in the place they died. However, this has been rectified since the Reapers now have access to Metatron's portal as shown in Angel Heart.

Procedure
The spell had three parts. It was essential to complete all three. However, the caster may vary among the three phases, as demonstrated by Castiel, who performed the first two, and Metatron, who completed the spell by performing the last phase.

Cut the Heart Out of a Nephilim
The first phase was to cut the heart out of a Nephilim. However, killing one without cutting the heart out appeared to have sufficed, as evidenced by Castiel stabbing the Nephilim's throat. Naomi described the process simply as "killing a Nephilim" when she read through Metatron's mind. According to Crowley's translation of the spell from the angel tablet, the heart of a Nephilim was one of the three ingredients, indicating that after Jane was killed, Castiel or Metatron cut out her heart.

Bow of a Cupid
The second phase was to secure a bow of a cupid. Castiel completed this phase by acquiring Gail's bow.

Removing the Grace of an Angel
The last phase was performed by Metatron, who removed Castiel's grace. Whether or not the grace required was that of the angel who performed the first two phases is unknown. However, the spell does not require all of the angel's grace as some of Castiel's remained afterwards and he was later able to retrieve it.

Mixing
When all of the ingredients are obtained, the spell caster must mix them until they are destroyed, and reduced to ashes. After they have been mixed properly, a smoke will arise from the ashes, to the sky, and the angels (apart from the spell caster) will be expelled from Heaven.

Appearances

 * Season 8
 * Clip Show  (first phase)
 * Sacrifice (second phase to completion)
 * ​Season 9
 * Heaven Can't Wait (mentioned and explained)

Trivia

 * Since Metatron cast the spell, Michael, Lucifer, and himself are the only confirmed beings that still have their wings. Since his grace has been removed, he no longer has access to his wings. The Grigori, Tamiel, still displayed the ability to teleport, so it is unknown wether he has working wings or he drew this power from the souls he consumed.