Jincan

"The poison is gaining much of its effects. I have never seen insects devoring each other inside a liquid, but that is a mirror to the society, right? Strong devours the weak. If insects can do it... why can't humans? Now, we will use this poison... and find our Master his place in this world."

- Christine Van Bilj looking at the bottle of Jincan Jincan Gu is a powerful poison from southern China. According to Ichabod Crane, it is made from the remains of powerful creatures that are placed into a container left to devour one another. Jincan plays an important role in the upcoming LOTM: Witnesses of Sleepy Hollow - War Arc.

Nature of Gu (wikipedia source)
Gu (simplified Chinese: 蛊; traditional Chinese: 蠱; pinyin: gǔ; Wade–Giles: ku) or jincan (simplified Chinese: 金蚕; traditional Chinese: 金蠶; pinyin: jīncán; Wade–Giles: chin-ts'an; lit. "gold silkworm") was a venom-based poison associated with cultures of south China, particularly Nanyue. The traditional preparation of gu poison involved sealing several venomous creatures (e.g., centipede, snake, scorpion) inside a closed container, where they devoured one another and allegedly concentrated their toxins into a single survivor. Gu was used in black magic practices such as manipulating sexual partners, creating malignant diseases, and causing death. According to Chinese folklore, a gu spirit could transform into various animals, typically a worm, caterpillar, snake, frog, dog, or pig.

In LOTM: Witnesses of Sleepy Hollow
The Jincan Venom was August Corbin's possession until he left it for his son, Joe Corbin, who hid it purposefully. Later, Joe had been cursed by Henry Parrish and Christine Van Bilj to turn into a Wendigo. When the Jincan was finally in Henry's possession, he used it to poison his mother, Katrina Crane, as part of the plan to bring Moloch to Earth. After being poisoned, Katrina lost some part of her free will and became Moloch's vessel, who consumed her energy inside out.

The only thing that could undo it was the Aurora Prism found by Benjamin Franklin when he was a mole inside the Hellfire Club. Despite the difficulties, Katrina struggled herself to assist Ichabod alongside Abbie, and with the help of Selina Strawberry, the Witnesses convinced Sheriff Leena Reyes.

With Abbie, Selina, Reyes and Katrina's help, Ichabod fter Crane used the Aurora Prism to prevent Moloch from being born and saved Katrina's life, the energy was shunted to Fredericks Manor where Henry had collected it and used the Succubus to fuel it until Moloch had been born.

Gu Meanings
The Hanyu Da Zidian dictionary defines 9 gu 蠱 meanings, plus the rare reading ye 蠱 "bewitchingly pretty; seductive; coquettish" [妖艷].
 * (1) Poisoning from an abdominal wug [腹內中蟲食之毒]
 * (2) In ancient books, a type of artificially cultured poisonous wug [古籍中一種人工培養的毒蟲]
 * (3) Ghost of a person [convicted of gu-magic] whose severed head was impaled on a stake [臬磔死之鬼]
 * (4) Evil heat and noxious qi that harms humans [傷害人的熱毒惡氣]
 * (5) Wug pest that eats grain. [蛀蟲]
 * (6) Sorcery that harms humans [害人的邪術]
 * (7) Seduce; tempt; confuse; mislead [蠱惑, 誘惑, 迷惑]
 * (8) Affair; assignment [事]
 * (9) One of the 64 hexagrams. It is formed from [the trigrams] Gen 艮 [☶ Mountain]) over Xun 巽 [☴ Wind) [六十四卦之一. 卦形为…艮上巽下]