Command Spells

The Command Spells (令呪), 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. The system was created by Zouken Makiri.

The shape of the seals is different for each Master; they reflect the magical characteristic of the magus. The Command Spells of the three magi from the Tohsaka family (Tokiomi Tohsaka and his daughters Rin Tohsaka and Sakura Matou) have the general form of a circle in reference to "harmony" or "wisdom", while Kiritsugu Emiya, Shirou Emiya and Waver Velvet have a sword. The Command Spells of Bazett Fraga McRemitz are shaped like a double-sided Fragarach, which is also a sword, and Ryuunosuke Uryuu's Command Spells remind him of intertwined snakes.

Usage
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.

If a given order is meant to apply over a long period of time or if the order is vague, the strength of the order will grow weaker. Of course, the opposite works as well: an order that is very specific will be more effective and will hurt the Servant if he disobeys - although it is still possible to resist the order at the cost of ever-increasing pain. For example, an order such as "obey everything I say" is largely meaningless. The case of Rin, who used such an order on Archer the first night after he was summoned, is an exception, and it had some effect as she was a superior magus. Archer mentioned that he feels a weight if he disobeys her, and received a boost when he follows her orders. On the other side of the coin, early during the 4th Grail War, Kayneth Archibald El-Melloi issued a Seal-backed order to his Lancer to "help Berserker kill Saber". This was something Lancer emphatically did not wish to do (desiring instead to duel her one-on-one and having saved Saber just moments prior), but because of both the power of the magus behind the order and the specific wording, Lancer experienced agony profound enough to cause visible convulsions when attempting to resist, and lasted mere seconds before being forced to give in.

If a Servant is fatally wounded, an order such as "heal right this instant" will result in the wound being temporarily sewed shut with a thread of prana, allowing the Servant to survive for a brief period; it does not, however, provide any actual medical treatment.

Even if the Master doesn't consciously activate a Command Spell, it can automatically be used unless it is an impossible order.

Number
Masters have three Command Spells that will vanish one by one as he/she uses them. A Master who uses up all three loses his or her right of authority over their Servant, but, practically speaking, this becomes a question of how close the relationship between Master and Servant is and how willing a Servant is to follow orders or assist anyway. If a contract is forcibly severed, the remaining seals lose their effectiveness and may disappear (although they do not in the case of Servant death - see below). Loss of the Command Seals does not indicate forfeiture of position in the Grail War, and a Master and Servant may continue to participate long after the seals are used up, if they so choose.

In the case where an existing Master makes a new contract with another Servant, the Master receives three new Command Spells - and accompanying bodily seals - dedicated to that Servant. When Kotomine made a contract with Lancer, he first stole the Command Spells to Bazett Fraga McRemitz, but the difference between a forced change of Master and a consensual one is unknown.

It is also unknown if the number will return to three if a Master first cancels his/her contract with one Servant to make a new one with another, but it didn't seem to be so.

When a Servant is killed, the color of the seals fade out and they look at best like a birthmark or a bruise, but they don't disappear entirely - Fate/Extra describes them as fading out to a light grey. Even after the war has ended, the Command Spells - and the resulting brands on one's flesh - remain, although a magus who loses their Servant to death also loses their status as a Master.

After the war has ended, it is possible to remain as a Master if the magus still has his/her Seals and his Servant.

Command Spells that disappear without being used are still stored within the Grail, so they can still be reused when making a new contract with another Servant who has lost his Master. But as there will normally be no more eligible magus, they will tend to come back to the previously selected Master. In the fourth War, when Kotomine lost two unused Command Spells at the death of his Servant and didn't make any new contract with a Masterless Servant, the two Command Spells were redistributed. In the end, all the unused Command Spells go back to the care of the supervisor. The supervisor can freely redistribute them without any restriction, and transfer like he would a regular magus seal.

Command Spells and Magic Circuits
Command Spells react with each other, so two Masters will know each other when they meet. However, as the Seals use prana to activate, if the Magic Circuits are closed, it will be difficult to tell if a person is a Master. However, as they are a different system than the Magic Circuits, it is possible to use them even if one doesn't have any Magic Circuit.

Receiving the Command Spells is a miracle, but once they have manifested, they become no more than a physical enchant. Thus transplanting them by pulling the Magic Circuits or performing a psychic surgery is possible. As the Command Spells are integrated with the Magic Circuits, forcibly ripping off the Seals is roughly analogous to tearing out someone's nerves; therefore, if done poorly, the unfortunate victim can end up permanently crippled. However, Seals can be transferred safely via careful magical operation and, as they are still present even on the dead body of a Master, it is still possible to recover them with the appropriate method after a Master's death.

As noted, it is possible to transplant the seals to another person, but it can only be done to a Master or a Servant. No matter how good a magus is, one cannot become a Master by stealing the Command Spells if one wasn't a Master to begin with; only the Grail can confer such status.

When Shinji Matou stole the right as a Master from Sakura using the "Book of the False Attendant", strictly speaking, he wasn't actually counted as a Master; one could say that the book itself served as his "Command Seal", and he didn't seem to know the Seals normally appear on the arm. Souichirou Kuzuki seemed to use a Command Spell on Caster, but he doesn't actually have them.

As the strongest Master of the fifth Holy Grail War, Illyasviel von Einzbern's Seals are specially made to handle Berserker.

Fate/Extra
In Fate/Extra's universe, the Command Seals are more or less the same as they are in the Fate/stay night universe, with one significant caveat: the Serial Phantasm which oversees the Grail War in Extra counts the loss of all three Command Seals, and thus the severing of the contract between Master and Servant, as forfeiture in the Grail War, and immediately terminates the magus in question the instant the third seal is used. Masters in the Grail War in Extra, therefore, effectively have two commands at their disposal instead of three, making them even more precious. They can also be in locations other then the hand and forarm. A unamned Master mentions his are on his lower back (And calls them a Tramp Stamp), much to his embarrassment.

Fate/Prototype
The Command Seals in Fate/Prototype have specific ranks and placements. They follow an motif. Each has a number of "wings" related to the appearances of the Seals, and an Angel Rank corresponding to one of the types of angels within the angelic hierarchy.

Position
The seals typically appear on the arm and/or hand. Shirou had his seals on the back of his left hand, as did the Fate/Extra Protagonist. Rin had them on the back of her right hand. Sakura's were also on her left hand, but they nearly covered her entire body when she became Dark Sakura in the Heaven's Feel route. Caster, when she stole those of Shirou's, received her seals on the back of her right hand. Kirei had the seals for Gilgamesh on his right arm, and those he stole from Bazett for Lancer on his left arm. Bazett had them on her left arm. Kiritsugu had them on his right hand. Ilya, meanwhile, is effectively covered in them from head to toe by design, as no other seal arrangement would allow her to control Berserker so completely.