Opening Lucifer's Cage

Opening Lucifer's Cage required a complex spell. It allows a caster to open Lucifer's Cage from Earth.

The Lucifer's Cage can be opened from almost any point on Earth, and not depending the main gateway which was located in St. Mary's Convent, Ilchester, Maryland. Dean can opened it in a house in Detroit and later on Sam opened it at Stull Cemetery. It implies that it has an existence in another dimension or a separate plane of existence, as implied by Dean's description of time passing differently in Hell.

Via breaking 66 Seals
The 66 Seals serve as "locks" on Lucifer's Cage that God prescribed or inseminated as events. Lilith, the first demon, was released by Azazel under Lucifer's orders, as she was described to have the capability to break the seals. In addition, Lilith herself was the last seal that can open the cage.

When Lilith killed by Sam (and break the last seal), in Lucifer Rising, her blood reveals the door of Lucifer's Cage and opened it.

Via Rings of the Horsemen
In, Hammer Of the Gods, the archangel Gabriel reveals posthumously, before being killed by Lucifer, that Lucifer's Cage, which was opened when the 66 Seals were broken, is still down in Hell and can still be used to contain Lucifer if it can be reopened and Lucifer tricked back into it somehow. He reveals, believing that Lucifer is not aware of it, that the original keys to the cage are the rings worn by the Four Horsemen of the Apocalypse. He suggests that if the Winchesters can gain all four, they will have the cage as an answer to stopping the Apocalypse from devastating the Earth and destroying Humanity. However, the Archangel reveals that this will not be easy as they must first get the cage door back open and then devise some way of tricking his brother back into it before shutting it again. In Swan Song, after collecting Rings of the Horsemen, Dean uses an Enochian incantation revealed to him by Death to open Lucifer's Cage. Dean says "Bvtmon Tabges Babalon" (which roughly translates "Open the mouth of the cave of the evil/wicked one") and the cage opens, but Lucifer shuts it by chanting a counter spell. Later in the episode, Sam uses the same incantation.

Dean/Sam opens the Cage with the following incantation: BVTMON TABGES BABALON Beh voh tah mo en tah beh geh sah bah bah loh en

(which roughly translates "Open the mouth of the cave of the evil/wicked one")

However, Lucifer closes the cage, with a counter spell: CHDR BVTMON kah hee deh rah beh voh ta mo en

(which roughly translates "Close the mouth")