Marble Phantasm

Marble Phantasm remake.gif|Arcueid Brunestud using Marble Phantasm on Roa in Tsukihime -A piece of blue glass moon-.
Image:MP.jpg|Arcueid Brunestud using Marble Phantasm on Roa in the Tsukihime manga.
 is the ability possessed by the Nature Spirits that are the Planet's sense of touch, allowing them to reconstruct the world through probability alteration. By connecting their will to the world, they can transfigure it into whatever environment they imagine. However, the same cannot be done with things like humans or animals, which exist independently of the world. Imagination Realization is purely the ability to freely transform one's surroundings.
The capacity of the actualization is proportional to the scale of the Elemental. The term "Elemental" usually refers to Spirits from nature when used by itself. The spiritual realm isn't a world separated from the real world, but localized regions thought of by the Elemental that creates them, such as legendary lands and countries of eternal spring are the products of the imagination of whatever Elemental rules over them; hence it is possible for a human to stray into it.
When Arcueid uses Marble Phantasm on Roa, she turns layers of the corridor's into a vacuum that had cut him like a knife would a radish. Although Roa himself was not affected, there was no way to avoid being chopped in pieces by the atmosphere, and Roa only narrowly managed to remain as just his ankles - Arcueid's imagination didn't go as far as having the floor dislocate.Tsukihime - Near Side: Arcueid's Route, 12/The World of the Moon - 11th day/October 31 (Sun.)
In the remake continuity, during her fight with Michael Roa Valdamjong, Arcueid Brunestud activates her trump card to change the corridor's shape to become an ethereal crystallized form of itself. This disables Roa's Thaumaturgical Foundation, sealing him in a confined space that is visualized as a cube that appears before Arcueid, then proceeds to swipe her claws over it, causing Roa's body to be disintegrated.Tsukihime -A piece of blue glass moon- - Moon Princess route - Day 13: "The Face of the Moon" This is portrayed through her Last Arc .
If Arcueid takes off her limiter, she can probably materialize an entire small village in the mountains. In locations where humans have made changes, it will take more time to first break it down.
The Skill Schwipsig is Anastasia's past nickname (means "little imp"), while also one of Viy’s abilities. It makes all forms of minor impossibilities possible. It enables small prank-level Marble Phantasms, such as transferring what the opponent is holding to her own hands or opening a crack on the ground and getting the opponent’s foot stuck there. It’s quite the absurd ability, but it’s unable to cause any lethal damage.Fate/Grand Order material VII - Anastasia Nikolaevna Romanova, Profile translated by ComunCoutinho
The concept works on "clustering illusion" theory of probability. Much like a mathematical metaphor involving drawing a white marble from a bag of black marbles with a one percent chance, Marble Phantasm is the ability to raise that chance to one hundred percent and definitely pick the white one amongst all the black ones. This remains within the laws of the world, but similarly, a Reality Marble would allow for all of the marbles to turn into white ones. This is something the world wouldn't naturally allow. It can be considered more efficient, but Reality Marbles can only specialize in that one aspect, while Marble Phantasm can perform any number of things. Reality Marbles can also affect things not of nature, so they can also be called superior in that sense.
==Users of Marble Phantasm==
*Nature Spirits
*Elementals
*True Ancestors 
**Arcueid Brunestud (Remake)
**Altrouge Brunestud
*Sumire
*Viy
==Millennium Castle Brunestud==
MillenniumCastleBrunestud-Remake.jpeg|Millennium Castle Brunestud in Tsukihime -A piece of blue glass moon-.
MCB.jpg|Arcueid chained in the castle.
The , originally the lair from Crimson Moon Brunestud and a piece of his Reality Marble in the mountains, is currently reproduced by Arcueid's use of Marble Phantasm that she calls home. 
The original master of Millennium Castle has already been annihilated, but since then, those True Ancestors that were able to form it, through their Marble Phantasm ability, were given the title of Brunestud and treated as royalty. True Ancestors, beings that have no concept of social stratification, call Arcueid the princess for this reason. It is existing in the location closest to the moon, not topographically, but where the world receives the most influence of the moon. It is the castle Arcueid sealed herself into, depicted as chaining herself to the throne, after getting tricked into drinking blood by Roa and killing other True Ancestors. Even without Arcueid around, the castle is still seemingly in existence, but without "life". To the True Ancestors, the castle was probably their absolute protection.
Moreover, the reason why the Millennium Castle suddenly appeared in the city of Souya in the Ciel route is simply because its True Ancestor lord (Arcueid) willed it into existence.
The Witch Swift Umbrella in the World of Notes. is said to be the "original form" of the Millenium Castle Brunestud.
==References==
it:Materializzazione delle illusioni
vi:Không Tưởng Hiện Thực Hóa
Category:Magecraft terminology‎
Category:True Ancestor terminology
Category:Elementals
Category:Nature Spirits
Category:Cosmology
Category:Terminology in Tsukihime
Category:Terminology in Fate/Grand Order
Category:Terminology in Tsukihime Remake