https://live.staticflickr.com/65535/...0c828474_c.jpg
Textbook of the Sunken Spiral Castle: A 50-line Mystic Code. It allows the summoning of an army of Horrors, water demons from the depths of the seas of another dimension, as well as High Thaumaturgy, Greater Rituals and ritual magecraft, regardless of the user's skill in magecraft in relation to the use of the grimoire. Rather than simply functioning as a tome of spells and curses, the book itself is a "monster" that functions as a Magical Energy Reactor core possessing its own enormous magical energy furnaces completely independent of its wielder's magical energy. It can either be read from as a regular tome for minor spells, such as summoning a single demon with "Cthulhu fhtagn", or it can be completely commanded by the user, causing the pages to rapidly flip by themselves as the tome provides the necessary incantations and its own independent power to conduct the summoning spells with an inexhaustible magic energy supply.
Depending on the verses used, this allows for the usage of a class of ritual magecraft that tens of magi couldn't accomplish together. Even if the user is not a legitimate magus and has no groundings in magecraft like Gilles de Rais himself, this grimoire, acting as the agent, can exercise summoning magecraft to compensate, allowing one to become a specialized summoner with this Noble Phantasm for as long as one possesses it. For this reason, Gilles de Rais can summon the sea demons and employ them. The Spellbook itself is constantly giving off magical energy, and if it is cut, rather than showing pages, it shows a glowing, unearthly substance. It is capable of regenerating damage caused to it under its own power, and the "wound" closes much like it would on a living creature.
The water demons, without a discernible torso nor appendages, are best described as masses of tentacles with circular mouth-like openings marked with shark teeth-like blades. They usually are shorter than a man but can also be summoned several times larger than one. Their appendages are heavily spiked, serrated and covered with either eyes, suction cups, spines, papulae or all of them. Each tentacle contains an additional mouth which split open to reveal them, and have some form of elasticity to their limbs to allow them to reach and bind their target from a distance. They also possess some regenerative powers to non-lethal wounds, even crippling ones such as lost limbs. Their innards spew a black mist-like gas that would cause lung corrosion in a normal human, and can spit a purple, viscous acid that is also a paralyzing agent. They are neither spiritual bodies or members of the Phantasmal Species, but rather creatures from an entirely different dimension with different natural laws, containing attributes in accordance with the deep sea system. They are summoned by using the blood and flesh of creatures, living or deceased, as a sacrifice, and they must constantly receive magical energy from the Spellbook. They can be guided, but the tome doesn't allow for direct control over the creatures. It can be said that it is "inviting" them, simply utilizing the magical energy and technique to open the door into the world. While one sea demon's fighting strength is generally not comparable to a Servant's, the Artifact's Anti-Army classification is not for show as it makes it possible to summon dozen of bodies in order to further compensate for an individual demon's fighting weakness with overwhelming numbers.
It is able to endlessly call them, revive them, and send them at any enemies as its wielder commands it. They will stay summoned as long as they receive magical energy, allowing Gilles to leave them as guards to his workshop while he is away. No matter how many are destroyed in close combat, their numbers will never decrease for it is possible that the flesh of the defeated demons, acting as mediums, will instantly spawn new ones to take their place; because of this, the Artifact has an excellent ratio of magical energy consumption to the amount of summoned demons.
