Ritual of Chüd

Ritual of Chüd is an eldritch psychic battle of wills used by the a group of 7 human misfit children called the Losers Club as the only means to defeat the nightmarish interdimensional fiend known as IT/Pennywise. It serves as a crucial plot element in the classic 1986 Stephen King horror novel It.

It (novel)
Bill Denbrough first found the information about this "ritual" when he discovered a book Night's Truth at the Derry Public Library within Derry Maine, where he also learned It was part of an obscure race of spider monsters called "Glamours" existed to many cultures under many different names. The Ritual was from an old Himalayan belief, a myth, that recognized It as a kind of monstrous shape-changer called the "Taelus". In the forgotten Himilayan tradition, a holyman and the Taelus overlap tongues, biting in towards each other, and telling each other riddles until one laughed despite the pain in this "content". If the Taelus laughs first, it gets sent away for a hundred years, while if the holy man laughs first the taelus gets to eat his soul.

As children, Bill Denbrough was the only one who engaged with It, being thrust toward the Macroverse, heading to the dreaded Deadlights, but his physical body remains put. Maturin the Turtle from the Macroverse who came upon before Bill because of the special significance within Bill and his 6 closest friends as seen and approved Maturin's cosmic superior Gan (otherwise knoen by his alias "The Other"), and he only offered advice that "–you must help yourself, son," and "you've got to thrust your fists against the posts and still insist you see the ghosts[...] once you get into cosmological s**t like this, you got to throw away the instruction manual." Bill began contending with It telepathically, biting his teeth into Its' tongue, saying "He Thrusts his fists against the posts and still insists he see the ghosts" in his father Zack Denbrough's voice again and again. Overall, the battle is but one of the Losers' optimism, imagination, unity, and faith over malice and rage. The Losers emerged victorious, but ignore the Turtle's advice to make sure they finish the deal, and It escapes, which the Losers suspect but were never sure of. So they formed the Blood Oath by shedding blood from the palm of each other's hand with a glass shard of a discarded Coca-Cola soda bottle, holding hands with each other in a circle and swearing themselves to come back to Derry should It return alive.

As adults, Bill Denbrough is the first to face It head on once again. However, without his childlike imagination, he is but weaker in the battle. It taunts him, saying that the Turtle died some time ago. Bill '"misses" It's tongue, and Beverly calls out that something is wrong, It is laughing. Richie Tozier quickly realizes something is wrong and screams out in his Irish cop voice, catching Its tongue and being thrown into this universal sprawl with Bill Denbrough. He rescued Bill from the Deadlights, threatens It with his voices, but they still struggle against it. As before, their bodies remain still within the real world, but Eddie Kasprak hears Richie calling for help, and rather than enter with them, he uses his aspirator as before to seriously hurt It within the physical world, yet it cost him his arm in the process and dying a bloody demise. It was able to break through further into It's lair, dropping eggs along the way that Ben stays to crush, as Beverly Marsh remains with poor Eddie's body. Richie reluctantly leaves Eddie and Bill leaves Audra to go further after It needing to ensure It stays dead this time. When they found It, they hit It with their collective belief and love and childhood nostalgia along with the power of the Other. Richie is knocked out, Bill crushes Its beating heart between his hands, and carries Richie, who he believes may be dead, back to the other Losers as they at last won and called the eldritch ancient evil It forever.

It (TV miniseries)
The Losers Club (also sometimes referring to themselves as the "Lucky Seven") battled the evil being It in the Ritual of Chüd (with the said ritual being different compared to its version in the novel) together (a small but urgent advice from local Irish policeman Officer Aloysius Nell,one of the few caring adults within Derry). The children believed that the precious metal silver had supernatural abilities, as seen in numerous monster movies. Because the children believed in it strongly, the silver became the real ultimate weapon that was used in the fight against It in his prominent dancing clown form Pennywise at the sewers beneath the town. Because Beverly was very good with a slingshot, the Losers' Club injured It the first time when Beverly shot a chunk of silver into Its skull now flashing with the Deadlights before It acrobatically jumps over towards a small water drain and retreated deep underneath the sewers. The Losers thought that they killed It, but were uncertain, so they made a pact to return to Derry should It ever resurface.

Now as grownups, Bill, Richie Tozier, Beverly Marsh, Eddie Kaspbrak (murdered by It) and Ben Hanscom found It's secret lair fulled of broken skeletons and web-covered victims within a cave deep within the sewers of Derry despite It's contemptuous warning via a floating phantom avatar of Pennyise's head to them at the sewers (though it is true no one can see It's eldritch true form, only what their minds can allow and comprehend). Once the five of the "Lucky Seven" found It's cave, the malevolent being finally challenge them to their second final confrontation, this time as a hideous giant spider. Yet the Ritual of Chüd ended almost the same way with Beverly shoot the familiar lost silver metal jewels later recovered by Mike Hanlon 10 ago during It's hibernation and one of the silver materials sucessfully hit the creature's glowing hindquarters comprised of Deadlights and fatally injured it. The Losers succeeded at last in killing the weakened foul beast by both punching his hindquarters and ripped out It's beating heart.