The Word of God

"Cut off the head, and the body will flounder. Waste not thy time nor thy breath on the Leviathan herd. Point thy blade at the heart of their master, for from him springs all their messages. Leviathan cannot be slain but by the bone of a righteous mortal, washed in the blood of three fallen: a fallen angel, the ruler of fallen humanity, and the father of the fallen beasts."

- - The Word of God.

"So ends the transcription of the sacred word for the defense of mankind. Into the hands of God's children thus passes the compendium of tablets."

- - Kevin Tran reciting The Word.

The Word of God was written and depicted by the angel Metatron, who ciphered it while God was forming creation. The Word was carved into an unknown number of stone tablets which were later locked in an underground vault in the core of the Earth (possibly multiple vaults).

It is breakable, however, the prophet destined to read it can re-connect it. It is written either in an ancient language or one not taught to angels, and only the prophet linked to it can read it. However it is not as straight forward as simply reading, and seems more akin to knowing how to translate it. It's also described as hurting their heads if they look at it for extended periods of time.

In 2012, Dick Roman excavated one of these tablets, which contained the secrets on how to kill the Leviathans. Crowley later got his hands on one somehow that contained information on demons. Castiel and Dean found one that holds information on angels in one of Lucifer's Crypts. It has been revealed that there is a whole compendium of tablets out there somewhere on the various beings in existence, including angels.

Known Tablets

 * Leviathans - How to slay the indestructible Leviathan.
 * Demons - How to imprison all demons in Hell forever and how to destroy them. It is said by Kevin to Crowley that it can also give a demon great amounts of power.
 * Angels - How to cast Angels out of Heaven. How to imprison all angels in Heaven. Grants God-like powers to any angel connected to it.

Documentation
It was written while God was in the process of creating life. It was eventually placed in the Earth's core, "the Vault of the Earth".

The Girl With The Dungeons and Dragons Tattoo
Top Leviathan, Dick Roman, sent another Leviathan to retrieve it at an airport, but Sam intercepted it. They don't know what it is or does.

Reading Is Fundamental
Having it, Dean breaks the shell that contains the script, which causes loud supernatural simultaneous lighting. They take it to Castiel who informs them that it is the Word, but is unable to translate it for them. He then drops and breaks it into three pieces upon teleporting away.

Kevin, a boy reluctantly turned into a prophet, tries to steal it, but Sam and Meg catch him. Upon touching the fragments, the tablet repairs itself. Kevin is able to translate the Word for the Winchesters, giving them at long last the information they need to kill the Leviathan.

There Will Be Blood
The tablet once again falls into the hands of Dick Roman who forces Kevin to translate it for him, by threatening to kill his mother.

We Need To Talk About Kevin
Crowley has gotten his hands on a second Word of God tablet, this one about demons and kidnaps Kevin to read it for him. Kevin learns from it that there is a way to open all of Hell's gates and directs Crowley to a gate in Wisconsin while he performs a spell to open it. However, Kevin tricks Crowley and actually performs a spell from another section of the tablet, a spell that destroy demons. Kevin flees with the tablet after killing his demon captors and hides the tablet, but first learns from it how to defend himself from demons including the effects of holy water and how to make a Devil's Trap. He also learns that there is a way to seal all the gates of Hell forever and banish all demons and informs Sam and Dean of this once they track him down.

What's Up, Tiger Mommy?
Kevin leads Sam and Dean to a bus station where he has hidden the tablet on demons in a locker. However, a corrupt security guard has stolen it and sold it to a pawn shop. Sam, Dean, Kevin and Linda Tran track the tablet to an auction run by the god of greed Plutus where the tablet is up for sale. Crowley and the angel Samandriel are among the bidders, but when the price doesn't get high enough, Plutus has Kevin added to the sale. Finally, after Mrs. Tran agrees to trade her soul, Plutus agrees to give the tablet to her. However, Crowley teams up with Plutus' assistant Beau and possesses Mrs. Tran to steal the tablet. In the confrontation that follows, Crowley escapes with the tablet.

A Little Slice of Kevin
In a desperate attempt to get the tablet translated, Crowley has all of the future prophets kidnapped, but none of them can read it until Kevin dies and they get chosen. With the help of a witch named Delta Mendota, Crowley finds and kidnaps Kevin and tortures him into reading the titles of the tablet's sections to him. Among the sections is a "personal note" from the angel Metatron who wrote the tablet in which he apologizes for taking his leave of God and Heaven and reveals that there is a compendium of tablets, something that interests Crowley greatly as he didn't know there was anymore besides the Leviathan and Demon tablets. Sam, Dean and Castiel attack the warehouse where Crowley is holding the prophets and the tablet, killing a few demons using the "demon bomb" spell from the tablet. Castiel confronts Crowley over the tablet and Kevin and as Crowley tries to flee with it, Castiel breaks the tablet in half. While the Winchesters get one half of the tablet, Crowley escapes with the other half and Sam and Dean, joined by Castiel become determined to find it.

Torn and Frayed
Kevin continues to try to translate the half of the tablet in his possession, albeit to no avail. Dean and Castiel later approach him for the list of ingredients to the demon bomb which is later used during an attack on one of Crowley's bases.

While being tortured, Samandriel talks about the tablets and reveals the existence of one on angels before the Winchesters and Castiel manage to rescue him. Calling Samandriel a traitor for revealing this, Naomi forces Castiel to kill him. She tells Castiel that any angel would rather die than reveal the existence of that tablet and implies that, like the demon tablet could be used to seal up Hell and all demons forever, the same could be done to angels with the angel tablet.

Trial and Error
After weeks of non-stop work, Kevin finally manages to translate the section of the demon tablet on how to close the gates of Hell. According to Kevin, the person closing the gates must do three trials and recite an Enochian spell after each trial. Kevin translates part of the instructions as "whosoever chooses to undertake these tasks should fear not danger nor death nor getting your spine ripped out through your mouth for all eternity." Kevin is only able to decipher the first trial which is killing a hellhound and bathing in its blood.

Kevin later calls Dean to inform him that he has discovered information on hellhounds on the tablet: "the dire creatures may be seen only by the damned or through an object scorched with Holy Fire." Sam and Dean decide to scorch glasses with Holy Fire so they can see a hellhound that is coming after people who have made deals.

Sam eventually manages to kill the hellhound with the Demon-killing knife using a pair of scorched glasses and casts the spell, completing the first trial the tablet mentions.

Goodbye Stranger
Having learned that the angel tablet is in one of Lucifer's Crypts, Crowley sets out to find it by torturing the locations of the crypts from Meg and having demons possess people who hold great knowledge of the town where the crypts are to find them. At the same time, Naomi sends Castiel to search for the tablet as well. When the Winchesters get involved, he initally lies to them, telling them that he is searching for Crowley's half of the demon tablet and that the demons are looking for a parchment that will allow them to translate it without a Prophet.

After Castiel rescues Meg, she reveals the location of the crypt with the angel tablet and she, Sam, Dean and Castiel travel there to get the tablet. As Meg and Sam defend the building, Dean and Castiel enter the crypt and Castiel recognizes the location of the tablet as it is in an angel-proofed box. Dean gets the tablet which is also shown to be encased in stone like the Leviathan tablet and Castiel, on Naomi's orders, tries to kill Dean for it. Eventually Castiel manages to resist her control and pick up the tablet. The angel tablet surrounds Castiel in a bright glow that severs Naomi's connection to Castiel and breaks her control over him. Castiel heals Dean and explains what happened along with the fact that he can tell that he must now protect the tablet from all threats including Crowley, Naomi and for some reason, Dean himself before disappearing. Naomi later tells Crowley that Castiel is doing what he is meant to do: protect the tablet from all threats.

At the end of the episode, Castiel is seen traveling with the tablet on a bus somewhere.

Taxi Driver
Kevin deciphers the second trial and reveals that Sam must rescue an innocent soul from Hell and release it into Heaven.

Due to his increasing paranoia and hallucinations that Crowley is taunting him in his head, Kevin hides his half of the tablet somewhere. Crowley later states that Sam and Dean got the good half of the tablet while he only got the half with useless information on it.

With the help of rogue Reaper Ajay, Sam manages to sneak into Hell through Purgatory and rescues the soul of Bobby Singer. With the help of Benny Lafitte, Sam and Bobby return to Earth where Sam releases Bobby's soul towards Heaven. Crowley intervenes, having figured out what they are up to, but Naomi stops him and frees Bobby's soul, allowing him to travel to his rightful place in Heaven and completing the second trial. Sam then casts the spell from the tablet that needs to be cast after every trial.

Kevin and all of his notes on the tablet are captured by Crowley who makes it seem like Kevin has simply run away, leaving Sam and Dean with no clues on the third trial, but Crowley without the tablet as Kevin hid it.

The Great Escapist
Kevin is brought Crowley's half of the demon tablet by two demons pretending to be Sam and Dean and he works on translating it while a message is sent to the real Sam and Dean prerecorded by Kevin. The message contains his notes on the tablet and they eventually lead Sam and Dean to Metatron. Metatron reveals that the Archangels want to take over all of creation and that the tablets are the key to it. Kevin eventually figures out that he is being tricked and confronts Crowley who starts to strangle him when he refuses to tell him anything but that Crowley has no idea of the power the tablet could have given them. Kevin is rescued by Metatron and takes the second half of the tablet with him. With that half, Kevin finally knows the third trial: cure a demon.

The angels led by Naomi finally track down Castiel, but as they interrogate him on the location of the angel tablet, Crowley arrives, having been told where they are by Ion. Crowley kills the other angel and forces Naomi to flee then pulls the tablet from where he has realized Castiel is hiding it: inside himself. He later takes it with him to Kevin and doesn't care about the power the demon tablet would give him as he has the angel tablet.

Sacrifice
Sam and Dean meet Crowley as part of deal to exchange the Demon and Angel tablets, though this was a ruse and they manage to capture the King of Hell. Later they get Kevin to try and translate the trial to lock the Angels back in Heaven, however he notes that the things Castiel did (slaying a Nephilim, taking a Cupid's bow) are not mentioned as part of the trials. It was later revealed to be part of a spell (the last part being to take an Angel's Grace) to cast down all angels from Heaven.

Heaven Can't Wait
The Angel tablet is more difficult to translate into English than the previous ones, but it is possible to translate it into proto-elamite cunieform however not even the prophet could decipher this. It was translated by Crowley, who revealed that the spell Metatron used to cast out Angels from Heaven was irreversible and heralded the start of a new world order.

Holy Terror
The Angel and Demon tablets are stolen from Sam and Dean by Gadreel, under Metatron's orders.

Road Trip
The Angel and Demon tablets are delivered to Metatron by Gadreel.

Meta Fiction
The Winchesters believe Metatron has obtained god like powers from the Angel tablet.

Do You Believe In Miracles?
Sam, Castiel and Gadreel realize that since Metatron's god-like power comes from a connection to the angel tablet, if they break the connection, he will be just a regular angel again and can be killed. While Sam goes after Dean to help face Metatron, Castiel and Gadreel attempt to sneak into Heaven to find the tablet. After Gadreel sacrifices himself to give Castiel a chance, Castiel searches Metatron's office for the tablet and finds it in his typewriter. Castiel shatters the tablet, removing Metatron's added power, but not before he mortally wounds Dean.

Trivia

 * The Leviathan tablet was excavated in Iran.
 * The Word of God can be restored to its original state by the prophet that is linked to it, as seen when Kevin Tran fixed the broken Word of God by bringing the pieces together.
 * The Word of God can yield numerous effects. When Dean removed the Leviathan tablet from its clay casing, it activated Kevin Tran's prophet abilities, generated storms, caused every pregnant woman within 100 miles to go into labor, and sent out a signal that alerted every angel to its release, which woke Castiel up from his coma. When Castiel took the angel tablet from Dean, it gave off a golden glow and caused Castiel to regain total control over himself, freeing his mind from the influence of Naomi. Sam speculated that touching the tablet had reset Castiel to his "factory settings." Kevin once taunted Crowley by saying that the Demon Tablet could have granted him power he had no ideas of. Later, Metatron was able to use the angel tablet to effectively wield the power of God by connecting to it. When Castiel broke the angel Tablet that Metatron was connected to and powering up with, thunder could be heard on Earth.
 * Since there is not any prophet since Kevin's death, the angel tablet will remain broken.
 * Metatron states that the Angel Tablet is "arguably the most powerful instrument in the history of creation".
 * Castiel has broken every single tablet
 * Castiel has broken every single tablet