The Rift Sealing Ritual is a ritual to seal a rift in space and time between realities.
After the coming birth of the Nephilim Jack opened a rift between the main reality and an alternate post-apocalyptic reality, the Winchesters and Crowley decided to use this ritual to seal the rift and trap Lucifer. As Dean distracted Lucifer, Sam and Crowley prepared the ritual before Crowley killed himself with an angel blade to complete it. The ritual took a few minutes to fully close the rift, resulting in the death of Castiel and Mary Winchester getting trapped with Lucifer when the rift closed.
A bowl is placed in a devil's trap which has a bunch of ingredients added to it including dead sea brine, mercury, lamb's blood and holy oil. The final ingredient is the sacrifice of a life. Once the life is taken, including potentially the caster taking their own, the bowl of ingredients glows and sends a small burst upwards. The rift then immediately begins to close though it takes a few minutes to close completely.