Ostium

“	This box is a monster trap, powered by dark magic. It pulls monsters inside and kills them. It was built by the Men of Letters.	”
	— Latika Desai's description of the box in Pilot

The Ostium, also known as the Monster Box, is a monster trap powered by dark magic that sucks and in and banishes monsters and demons.

History[]

Early History[]

At some point in the distant past, the Ostium is constructed as a weapon by the Men of Letters. It is eventually hidden in some tunnels below a New Orleans crypt guarded by a Loup-Garou watchdog. They also heavily ward the tunnels so that demons can't get inside.

In 1972, after learning about the danger of a possible Akrida invasion, Samuel Campbell begins searching for the box with Ada Monroe's help as the box is the only thing that can stop the Akrida. Presumably aware of the threat as well, demons start looking for the box too.

The Winchesters[]

In Pilot, Samuel is able to locate and open the entrance to the tunnels where the Ostium is located, but he is attacked and vanishes before he can retrieve the box.

Following her father's instructions, Mary visits the Men of Letters Clubhouse with the help of John Winchester where she finds a file containing a schematic of the box showing how to open it. At Ada Monroe's shop, John, Mary, Latika and Carlos find an old book with information about the box in it and a piece of paper containing numbers written in Samuel's handwriting which John determines are coordinates to the box's location in New Orleans.

In the tomb, the group finds the open entrance to the tunnels, but no sign of Samuel. In the tunnels, John and Mary find a large stone chest containing the Ostium, but they are attacked by the Loup-Garou watchdog. While John stays behind to hold the monster off, Mary returns to the surface with the box where a demon possessing Ada demands the box. Using her earlier study of the schematic, Lata manages to activate the Ostium which exorcises the demon from Ada, draws the demon inside of itself and banishes it. At the same time, John is able to kill the Loup-Garou that had been guarding the box.

Returning to the clubhouse, Ada reveals the threat of the Akrida and that Samuel had sought the box as it is the only thing that can stop them, intending to use records in Savannah Men of Letters office to find where the monsters will cross over and then use the box to stop them. With Samuel still missing, John, Mary, Ada, Lata and Carlos depart for Savannah to try to find Samuel and continue his work.

In Teach Your Children Well, Lata tries to use the Ostium against three attacking zombies, but it fails to activate.

In You're Lost Little Girl, the Ostium is still not working, and the group attempts to track down the partner of the demon that had possessed Ada in the hopes of finding out more information on it. After being captured, the demon reveals that he and his partner had intended to find the Ostium and trade it to the Akrida Leader in exchange for being spared when the Akrida wipe everything out. The demon insists that the Akrida are too numerous to stop, even with the box and he doesn't know anything about its workings as the other demon was the one who was more detail orientated.

In Art of Dying, Lata mentions that, despite all of the Monster Club's research, they still haven't figured out how to make the Ostium work again.

In Hang on to Your Life, it's revealed that the Ostium was broken by being used to banish the Akrida Leader and several other Akrida. Millie Winchester takes it home with her in an attempt to fix it while Samuel and Ada search for a different magical solution to defeat the Akrida Queen.

In Suspicious Minds, Millie mentions that she's so far had no luck in fixing the Ostium. Jack Wilcox also reveals that the Men of Letters were able to use it to banish most of the Akrida from Earth during their 1957 invasion at the cost of severe casualties to the Men of Letters. However, several Akrida were able to remain hidden on Earth at that time, including the Akrida Queen.

In Hey, That's No Way To Say Goodbye, the Monster Club decides to use the repaired Ostium in reverse and Dean's Journal to attempt to bring Dean Winchester back from where Joan Hopkins banished him. However, the Ostium's polarity can only be reversed at midnight so John, Carlos and Samuel hold off Joan to buy the others time to use the Ostium. Feeding the Ostium Dean's journal and pressing the symbols in reverse, Lata succeeds in bringing back the Impala which is able to kill Joan as it is not of their world. Jack Kline later returns the journal to Dean.

Powers and Abilities[]

The Ostium is a very powerful device capable of banishing beings to other worlds.

Exorcism - The Ostium is capable of pulling beings from their vessels, pulling a demon out of Ada Monroe and the Akrida Leader out of Rockin' Roxy.
Portal Creation - After being powered through an object connected to the destination of choice, the Ostium can generate a portal to banish beings from its world. By reversing the polarity, it can be used to summon beings and even objects back.

Weaknesses[]

Multiplicity - Being used to banish multiple Akrida from the world at once broke the Ostium. However, with some time and effort, Millie Winchester was eventually able to repair it.