Fate Eternity

In early 2012, I came up for an idea for a role playing adventure based off of the Fate/ universe, specifically Fate/Zero. I pit seven of my friends as "masters" and I role play as the servants, who are each based off of separate series (both personal and anime-based). Caution as many links may contain Spoilers for the Fate universe.
== What is the Grail War? ==
The Grail War is essentially a large battle royal against seven individual magi call "masters". They eliminate each other one by one until the last one is standing. That master and servant get a wish from the Holy Grail (no, an even MORE powerful one) for anything that they wish. However, espionage and tactics are usually more useful than brute force, so there is some planning involved.
== What are Servants? ==
Servants are Heroic Spirits summoned by the Holy Grail. Once summoned, they can be classified as familiars as long as they are bound to a Master. Servants are legends from the past, present, or future. Because summoning even one heroic spirit is a miraculous occurrence, summoning seven in their pure forms would be beyond the Holy Grail's power. Thus, to facilitate the process, Servants are summoned into one of seven vessels prepared beforehand. These vessels are classified based on their primary roles. Heroic Spirits can be summoned into any "class" that reflects the abilities they had in life.
Although too powerful to be controlled by humans, the prospect of having a wish granted by the Holy Grail serves as incentive cooperate with a Master. A Master who is chosen to participate in the Holy Grail War possesses three Command Spells that, when invoked, forces the Servant to obey the Master's orders. However, few Servants actually appear to have a wish, with only True Assassin and Saber expressing theirs while the others are either content to serve their Master or have other goals entirely.
In order to call forth a specific Servant, a material connection between the summoner and the Heroic Spirit is required. This is particularly true if one wishes to summon an exceptional Servant. For example, the Einzberns used Avalon, the sheath of Excalibur, in order to summon Saber, and a slab of rock from a temple to summon Berserker in the fourth and fifth Holy Grail Wars respectively.
When summoned, Servants are imparted with knowledge of technology, culture, science and terms of the era they were summoned into, as well as skill in at least the language of their Master, if not all languages. This is largely to prevent Servants from eras significantly before the era of a Grail War in question from suffering crippling culture shock which would otherwise prevent them from fulfilling their duties, and also enable them to blend with that era society. This can be understandable by such problems:
*A Servant terrified of modern technology (such as electronic devices) and believes them to be sorcery.
*A Servant cannot cope with modern era surroundings and thus suffers from depressions. This can also happen to a Servant that is summoned in his past life homeland and finds it is altered by modernization.
*A Servant finds modern sciences ridiculous and even comical (such as the world is spherical and revolves around the Sun).
*Limits the abilities of certain Servant classes. For example, an Assassin dumbfounded by modern security systems; a Saber, Lancer, or Archer that fails to understand modern weaponry; a Berserker that is confused by modern surroundings and thus goes on a rampage; a Rider who is unfamiliar with driving modern vehicles; or a Caster that is superstitious of or easily fooled by electronic devices.
*A Servant behaves in a manner that attracts the attentions of modern civilians, or using weapons against them, and thus apprehended by the authorities, or carted off to lunatic asylum.
Servants can revert to spirit form when not in battle at will to reduce the burden on their Masters. In this form they can pass through inorganic substances that aren't dense with mana; they are also invisible to the naked eye (except for the Master they connected with) and most forms of scrying in this state, facilitating the concealment of their identity. When Lancer invaded the Emiya mansion, he used his spirit form to infiltrate the house. He subsequently reverted to physical form to drop from the ceiling into the living room. They cannot be affected by normal interference when dematerialized, but need to materialize for battle. As Human Spirits are they able to consume the souls and minds of people and convert them into energy. Their basic abilities do not change from such nourishment, but they become tougher and their magical energy capacity increases.
It is to be noted that originally, the Servant system was designed to summon only the souls of "true" heroes - benevolent, honorable, and selfless protectors of humanity and justice. But since the corruption of the Holy Grail in the third Holy Grail War, evil spirits can be summoned. These entities can still be considered to be Heroic Spirits if they were widely worshipped, respected, or feared in life.
=Classification of heroes=
Heroic Spirits summoned by the Holy Grail are placed into one of seven categories. The seven standard classes are Saber, Lancer, Archer, Rider, Caster, Assassin, and Berserker. 
*Saber: Servants placed within this class are agile and powerful melee warriors. It is commonly assumed to be the best class overall, with high ratings in all categories. It is one of the three Knight classes, together with Lancer and Archer and also possesses the Riding skill like the Rider class.
*Lancer: Servants placed within this class are very agile and skilled with long-range melee weapons, such as spears, lances, etc. It is one of the three Knight classes, together with Archer and Saber.
*Archer: Servants placed within this class are usually proficient with projectiles and can survive longer without a Master nearby, thanks to their special ability Independent Action; the strongest Archers can be difficult to control at times, in fact, due to their near-total independence from their "Masters". It is one of the three Knight classes, together with Lancer and Saber.
*Rider: Servants placed within this class place emphasis upon speed and powerful Noble Phantasms, which often include their mounts. Their special skill is Riding, which allows them to fully utilize abilities of their mounts (which can range from simple horses to mechanical vehicles to divine or supernatural creatures.).
*Caster: Servants placed within this class are adept in magecraft and have a special ability akin to Reality Marble, called Territory Creation, which alters or creates space around them to enhance their sorcery.
*Assassin: The Assassins' special ability is Presence Concealment, which allows them to remain undetected. Offset by their stealth is their weak combat skills. Due to this, Assassins often target Masters instead of Servants.
*Berserker: Servants placed within this class are always incarnations of heroes who have gone berserk on their lifetime. This trait allows them to use the special ability Mad Enhancement, which trades their consciousness (i.e. sanity) for a large power boost. Most Masters are incapable of controlling their Servant once Mad Enhancement has been activated, which eventually results in their death.
(much of this data was taken exclusively from the Type Moon Wiki)
== What do I have to do to win? ==
A master is only considered to have won once all other servants and masters are deceased (or otherwise unable to continue). It is possible to "win" if the grail war is taking too long, at which point the grail itself chooses the winner (much like it can choose masters in time of need). This means that their own servant has to die as well, though they can be ordered to kill themselves by using a command spell. 
== What are Command Spells? ==
The Command Spells, or Command Seals, symbolize (and, when used, enforce) the absolute authority of a magus over a Servant, and are the holy marks that appear on the body of the magi who become Masters for the Holy Grail War. Each Master gets three at the beginning, and the shape depends on both the Master and Servant. 
The seals are three absolute orders that can either restrain or reinforce the action of a Servant, to the point of making it perform an otherwise impossible action. If it is within the scope of the prana of the Master and the Servant, then it can be realized through the power of a Command Seal-backed order - even if it is something the Servant isn't normally able to do. Truly impossible orders, such as those requiring real Magic, cannot be accomplished. For more information, click here.
== Who are the characters? ==
Unknown. All that is known is that there is a member of the Tohsaka and Matou families are involved. Whether or not the Einzbern's are participating is unknown, but there are rumors once again of them hiring out a certain member of the Kiritsugu family...
As far as location, as the battle is set in Sigil, which is a very large city between dimensions. The city itself is in the Dungeons and Dragons universe. Because of the fact that there could be anyone traveling through the city, you can't necessarily see a recognizable character and instantly attack it. However, it is possible for two masters to meet and instantly know that they're masters due to how the command spells react.