Kah-Gash

Kah-Gash is a mythical "weapon" from Darren Shan's The Demonata series.

Demon Thief
He gives Kernel tons of advice throughout the book.

Legend of both humans and Demonata says that the Kah-Gash is a weapon that has the potential to destroy the human universe and everyone in it or all the demon universes and all the demons in them. When they are combined together they form an all and powerful weapon that is potentially deadly to all. The Kah-Gash is also a living thing that has tried to protect both realms but has failed due to the blood thirst of the Demonata.

The Disciples, a group of mages from the series, have the ultimate goal of finding the Kah-Gash and using it to destroy the demon universes. In Demon Thief, Nadia had a vision that a piece of the Kah-Gash would soon be found. It turns out that the "piece" is Kernel Fleck. Kernel believes that he is the Kah-Gash due to the fact that he can open a window to the location of anything in any universe that he concentrates on, except something that is where he currently is, and he is unable to open a portal to the Kah-Gash.

Slawter (book)
Grubbs thought it was his magic who instructed him of the use of magic was actually the Kah-Gash.

Demon Apocalypse
In Demon Apocalypse, it is revealed that Grubbs Grady and Bec, the other two protagonists in the series, are also the other two pieces of the Kah-Gash. When the three of them channel their magic powers together, they are able to perform feats of magic that break all previous rules of the art, first using their power as a way to travel back through time.

At the end of Demon Apocalypse, Beranabus intends to go with Kernel and Grubbs to study more about the Kah-Gash and how to control its powers. It is assumed that the main goal for the rest of the series will be the quest to harness this power to destroy the universes of the demons. Near the end of wolf island Grubbs finds out that he is probably going to destroy his universe with the Kah-Gash

Death's Shadow
Bec possed the Kah-Gash's memories so she can absorb memories whoever she touch.

Wolf Island (book)
He tells Grubbs that he's the control mechanism and can become the Kah-Gash. In Wolf Island (location) he give Grubbs instruction on how to survive in Wolf Island. He even tells him to become a Werewolf to fight the werewolves.

Dark Calling
The history between the Kah-Gash, Old Creatures, and Demonata are revealed.

In Dark Calling reveals that both the Old Creatures and the Demonata are creatures of the original universe which preceded the two universes in the series. This universe was structured like a chessboard; it consisted of sixty-four squares, half of them White and Black in chess and half of them black, each square containing infinite space within. The Demonata inhabited the white squares, the Old Creatures the black; the different zones were kept separate by a force which the Old Creatures called the Kah-Gash. While the Demonata were capable of reproduction, the Old Creatures were sterile, but this did not bother them; since time did not exist in the original universe, everything therein was ageless and immortal. They can still get killed.

Originally, the peaceful Old Creatures contented themselves with exploring their realms, undisturbed. The Old Creatures and the Demonata were unaware of each other, and it is stated that they were never intended to mix. However, out of curiosity, the demons eventually crossed into the black zones, discovered the Old Creatures, and attempted to wipe them out. At first the Old Creatures fled, hoping in their innocence that the demons would lose interest and leave them alone. When it became clear that this would not happen, the Old Creatures were forced to engage the demons in open war.

As the conflict escalated, pressure was put on the Kah-Gash, and it ultimately fractured under the strain. When this happened, the entire universe collapsed into a single speck, exploding a split-second later in what came to be called the Big Bang. The explosion formed two new universes: one (this universe) for the Old Creatures and ultimately the numerous species which developed on various planets; the other for the Demonata. The Kah-Gash split into three pieces, which for the next several billion years moved between the two universes inhabiting various life forms. Its last act was to create structures separating the universes, so that the two groups would never come into conflict again.

Following the explosion, time came into existence; everything in both universes began to age, and therefore became mortal. The Old Creatures accepted this, but the Demonata were determined to regain immortality. They set out to re-assemble the Kah-Gash, which would enable them to reverse time and restore Old Universe. Realising that this would mean destruction for all the life forms which had developed in the new universe, the Old Creatures were determined to thwart the demons. Whenever the Demonata found a piece of the Kah-Gash in their universe, the Old Creatures launched a raiding party which destroyed the form the piece inhabited, thus freeing the piece from the demons' clutches. This continued for millions of years, but as the casualties suffered by the Old Creatures rose, they realised that continuing with this strategy would ultimately lead to their extinction, given their inability to reproduce. They accepted this, and devised a way to ensure that others continued to fight the demons after they were gone.

Personaility
In Wolf Island (book) Grubbs said his personality is just like him escpically the way he sneers or says sarcaticallly.