Blood Fort Andromeda

is the Temple of Blood that surrounded the Shapeless Isle which was the home of Medusa and her sisters, turning it into a palace of darkness, dyed crimson from blood, where the sun didn't shine. 
The temple, known to petrify those who embark on the island and devour them, was a bounded field constructed by the Mystic Eyes Medusa possessed. By magnification of the Mystic Eyes' projection, a fixed conceptual field is substituted into "the inside of her eyes", and the life force of those inside it is plundered. An absorption power that literally "dissolves the body" of ordinary persons without any Magic Resistance. Even Heroic Spirits will have their life force plundered as long as they are inside the barrier.Fate/Grand Order material I - Medusa, p.206-213 (translated by castor212 on Beast's Lair) Medusa is able to implement it as a Bounded Field of blood that she uses to primarily absorb Magical Energy by dissolving any caught live humans and reducing them into red blood and organic ooze. Using her blood as a material component, she sets up a number of sources around an area, taking the form of magic circles placed as predetermined points, to slowly build up energy without leaving a single trace of her existence. It is impossible for Rin to completely destroy it as new circles constantly appear and old ones are restored. She can only delay its operation date by constantly removing as many circles as possible. It takes over ten days to completely store enough energy to activate the full power of the field, but it can still be activated at any time once the foundations are complete. It damages the leylines of the area once it is completely set up, so it cannot be reactivated on the same land twice in succession. It leaves a general listless feeling around the area, and Shirou senses the barrier by seeing an image of the area covered with membranes and the people looking like empty dolls while smelling the sweet scent of honey from an insectivorous plant.
bloodfort.jpg|The Temple of Blood on the Shapeless Isle
BFAMagicCircle.png|Blood Fort Andromeda's Magic Circle, shown on the Craft Essence from Fate/Grand Order
Templeseals.jpg|The Magic Circles placed around the school
Rider activating a Blood Fort Circle.jpg|Medusa activating a Blood Fort Andromeda Magic Circle.
Blood Fort deactivating.gif|The Blood Fort deactivating after Medusa dissipates.
Immediately following the placement of these circles, people within the affected area will only have their life force sapped slightly. Once activated, it forms an advanced Bounded Field almost on the level of Magic. It creates a crimson dome-shaped Bounded Field resembling a gigantic red eyeball around the area of operation, and it tints the area in crimson red that makes a person think that blood is seeping into their eyes. The barrier acts like a separate plane that completely cuts the affected area from the rest of the World, cuts off all escape routes for fleeing enemies, and Rin is left unable to contact Archer. As the barrier is conceptual, if it's pushed too far it will actually transform into the Shapeless Isle itself, which would be ironic for Shinji to invoke the place Perseus escaped. Naturally, from outside the Bounded Field, the area appears normal as usual and the red sky and dome cannot be seen at all, but the interior is stained with blood, as its name suggests. Victims within the barrier are quickly dissolved into blood as if they were inside a stomach upon activation, and its magical energy is given to either Medusa or her Master. Those with a proper amount of magical energy or with knowledge of thaumaturgy are able to resist the Bounded Field, such as a Servant or a magus respectively, but those without any are instantly drained. Even then magus can only resist Blood Fort Andromeda for a short amount of time. Thus, it is not a Noble Phantasm to be used for combat, but rather a Bounded Field created by Medusa to efficiently gather blood to drink for mana. If the Bounded Field is activated without the proper energy, it can take up to a number of minutes to completely dissolve the victims. If Medusa has a stronger master, such as when switching from Shinji to Sakura, the effect of the field will also become stronger. It is completely controlled by Medusa, and it will continue to stay active even after she dies. It will only be deactivated through her own will or once her body dissipates.
drain.jpg|Students in Shirou's school being drained of their energy.
Students being drained by the Blood Fort.jpg|Students being drained by the Blood Fort in the Unlimited Blade Works anime.
Sakura affected by the Blood Fort.jpg|Sakura unconscious due to the Blood Fort
The Blood Fort affecting the skin of the students.jpg|Students' skin becoming bloated in the Unlimited Blade Works manga.
Shirou & Rin affected by Bloodfort.gif|Shirou and Rin affected by the Blood Fort.
Those under the effect of the weakened barrier almost instantly collapse unconscious and begin to convulse and foam at the mouth due to the dense air. Stronger people can resist it for a small amount of time, while weaker people will instantly have their skin start to melt, have inflammation resembling a keloid, and their eyes will look like those of a dead fish. Those closest to the origin of the barrier will suffer the most severe effects, such as their blood being instantly vaporized and having the look of pale wax dolls piled like corpses. Someone with a slight resistance, such as Shirou, will feel nausea, dizziness, a sensation of being extremely hot, and instant discomfort as if their senses were revered. They will have trouble breathing as if the oxygen had suddenly dissipated. If the barrier is removed quickly enough, those furthest away from the origin will wake up as if they were sleeping and get away with a stay in the hospital for what amounts to severe malnutrition and slight memory loss. Those closer to the source however will suffer from side effects from having their life force drained, including scars and necrosis on the tips of their limbs from the melted skin, physical disabilities such as being on the verge of blindness, and mental scars from oxygen deprivation.
It's shown in the Heaven's Feel route that Blood Fort Andromeda can also affect Servants, as it drains mana from Archer. This was due to Rider being fed a sufficient supply of mana by her Master Sakura and was able to return to being at full power.
Rider explicitly stated in Fate/hollow ataraxia that, should Sakura wish it, she's prepared to summon a Blood Fort Andromeda on the scale of Fuyuki City, something she claims would put the Temple of Medea to shame and sacrifice the whole town.Fate/hollow ataraxia - Rider's Room: Night - Monster
In Fate/Grand Order, Blood Fort Andromeda is utilized as a Personal Skill, with decreased output values due to not being a True Name release.
==Pandemonium Cetus==
 is the Noble Phantasm of Gorgon. By renouncing to her last vestiges as a goddess, the shadow of her former self that she becomes at the very end, and the monster that was her (original) self's foundation, the “Gorgon/Monster of Gorgon”, is temporarily materialized. All organic life within the designated territory is liquefied and anything above that is instantly petrified with a zero percent chance of ever returning back to normal. It instantly robs the lives of humans, and even first class Servants are given severe damage.Fate/Grand Order material IV - Gorgon, p.352-363, translated by castor212 at Beast's Lair.
Pandemonium Cetus is a strengthened version of Blood Fort Andromeda. It does not require a set up time and can be activated with just the release of its True Name. However, its effectiveness is lowered somewhat against inorganic-type opponents.
It is a truly terrifying Noble Phantasm as the Hero Slayer, Gorgon, emerges from the servant that had once desperately held onto the last threads of her past self. 
Within Babylonia, once Pandemonium Cetus had been used it was unable to petrify Tiamat however it was capable of breaking the damaged horn that successfully grounded her back to the earth. Though this was after Quetzalcoatl had attacked Beast II. 
==References==
vi:Blood Fort Andromeda
Category:Noble Phantasms
Category:Anti-Army Noble Phantasms
Category:B rank Noble Phantasms
Category:Bounded Fields
Category:Mystic Eyes
Category:Spells
Category:Conceptual Weapons
Category:Effects on the level of Magic
Category:Noble Phantasms introduced in Fate/stay night
Category:Noble Phantasms of Medusa