Command Spells

The Command Spells (令呪), or Command Seals, are the absolute authority of a magus over a Servant, they are the holy marks that appear on the body of the magi who become Masters for the Holy Grail War, and become part of his body. The system was created by Makiri Zouken.

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

Usage
The seals are three absolute orders that can both restraint or reinforce the action of a Servant, to the point of making him perform an 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 an order of the Command Spell - even if it is something the Servant isn't normally able to do.

Although, if the order is meant to apply on a longer 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 it, at the cost of an increasing pain. For example, an order such as "obey everything I say" is meaningless. The case of Tohsaka Rin, who used such an order on the first night, is an exception, and it had some effects as she is a superior magus. Archer explains that he will feel a weight if he disobeys her, and will receive a boost when he follows her order.

If a Servant is fatally wounded, an order such as "heal right this instant" will result in the wound being temporarily sewed with a thread of prana, allowing the Servant to move for a bit; though it doesn't give any actual medical treatment.

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

Number
The Master has three Command Spells that will vanish one by one as he uses them. A Master who uses up all three loses his rights of authority over his Servant, but that is, practically speaking, a matter of how well their relationship goes. If a contract is forcibly severed, the remaining seals lose their effectiveness and possibly disappear.

In the case where a Master makes a new contract with another Servant, the number of Command Spells he can use for that Servant is in its initial state - three. When Kotomine Kirei made a contract with Lancer, he first stole the Command Spells to Bazett Fraga McRemitz, but the ifference 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 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 actually go away. Still, the magus loses his qualification as a Master. Even after the war has ended, the Command Spells remain.

After the war has ended, it is possible to remain as a Master if the magus still has his 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 Kirei 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, ripping off the Seals is the same as pulling out the nerves; therefore, if done poorly, the person can end permanently crippled. However, a magical operation can avoid that. Also, 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 the Master's death.

It is possible to transplant the seals to another person, but it can only be done to a Master or a Servant. However good a magus is, he can't become a Master by stealing the Command Spells if he wasn't a Master to begin with.

When Matou Shinji took the right as a Master from Sakura using the "Book of the False Attendant", strictly speaking, he wasn't actually counted as a Master; you could say the book itself was the Command Seals. He didn't seem to know the Seals normally appear on the arm. Kuzuki Souichirou 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.

Position
The seals basically appear on the arm and hand. Emiya Shirou has his seals on the back of his left hand. Tohsaka Rin has them on the back of her right hand. Illya has them on her entire body. Matou Sakura's are on her left hand, but it covers almost her entire body when she becomes Dark Sakura. Caster, when she stole those of Shirou's, got his seals on the back of her right hand. Kotomine Kirei has 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. Emiya Kiritsugu has them on his right hand.

Source: the dictionary resource at Jonnobi, and the Tsukihime Laboratory entry.