The Hellmouth is an entrance to hell that manifests as the open jaws of an infernal beast. Depictions of Hellmouths were common during the Middle Ages and Renaissance in manuscripts, and even as dramatic mechanical set pieces in theatrical productions.
Detail of The Mouth of Hell, from the Book of Hours of Catherine of Cleves, 1440
Vision de l’Enfer (Vision of Hell), from Les Visions du chevalier Tondal, 1475
Ludolf of Saxony, Inferno, from Speculum Humanae Salvationis, 1455
Lambert of Saint-Omer, Liber Floridu, 1250 – 1275
Detail of Jugement Dernier – Damnés (Last Judgement – The Damned Souls), 1492
Depiction of The Devil (almost certainly) surrounded by demon names and corresponding sigils from “Le serpent de la Genèse” (The Serpent of Genesis) Volume 2, by Stanislas de Guaita, 1920. Source: Embassy of the Free Mind
El Tío (The Uncle) is the devil-like spirit who rules over the mines of Cerro Rico in Bolivia. Statues of this “Lord of the Underworld” can be found all throughout Cerro Ricco’s mines, with offerings like cigarettes, coca leaves, and alcohol left for protection and appeasement.
“Miners may be Christians when above ground, but when in the mine, El Tio is their only god.”
Seals and characters for summoning the greater demons Lucifer, Beelzebub, and Astaroth. In order of effectiveness, the symbols must be drawn in either: the sorcerer’s blood, the blood of a sea turtle, or engraved on emerald or ruby. From Grimorium Verum (16th Century) and The Grand Grimore (18th Century). Source: “The book of black magic and of pacts”, A.E. Waite, Embassy of the Free Mind
The Goetic Circle of Black Evocations and Pacts, to summon Satan for a deal. The circle is formed from human skin, fastened by nails from a coffin of an executed criminal. A parricide’s skull, goat horns, a bat drowned in blood, and the head of a black cat who was fed human flesh must be placed around it. From The Book of Black Magic and Pacts, A.E. Waite, 1910. Source: Embassy of the Free Mind