Virago Magic

Virago Magic (ビラゴ 魔法 Birago Mahō) is a Holder Magic, as well as a sub-species of Card Magic, used by Virago Spirit Mages that involves the summoning of Virago Spirits.

Description
Virago Magic is a Magic in which the user summons Virago Spirits, a female race of Spirits designed to fight as soldiers, through the use of specially designed cards. Unlike the Celestial Spirit Keys, of which there can only be one key for each associating Spirit, the Virago Spirit Cards appear to be mass-produced, much like cards for a card game would be; as such, different mages can come into possession of the same type of Spirit Card, and it is in fact vital for a Virago Spirit Mage to collect multiple cards of their spirits. Virago Spirit Cards take a portion of the user's Magic Power to summon the spirit directly from Niflheimr (ニフルーイームル (領域の少女) Nifurūīmuru; Norse for "Abode of Mist", Japanese for "Domain of Maidens").

Summoning
To obtain a Virago Magic Card, the user does not simply go out and purchase them; while these cards can be sold to magic shops that will happily sell them for Jewels, a Virago Spirit Mage is introduced to their first Spirit usually by the act of conducting the Summoning Ritual (お召し儀典 Omeshi Saishi). To initiate the ritual, the prospective Virago Spirit Mage must first create seven magic circles in the ground, six centered around the focus circle, connecting each circle to the primary one in the center. The mage then channels their magic power into the foremost circle, which spreads throughout each and every circle, lightning them up with ghostly pale flames, before the energy is poured into the center, and seventh, circle, which glows bright white. This energy itself is sent directly to the Niflheimr, and the first Spirit who takes the magic offering will materialize itself physically before its new Master.

From the moment of the summoning, this particular spirit is now tied to its Master, and, through a combination of its magic power, and the Master's, the spirit creates a card, through which it encases itself when after, until it is needed for battle. While the amount of spirits a user can summon at any given time depends on their magical energy, the maximum one summon from any ritual set simultaneously is a total of 10 spirits; the minimum obviously being one.

This contract of sorts, however, is disturbingly easy to shatter; if a different mage obtains a card in use, and summons the spirit with their own magical energy, that spirit becomes tied to them, and they become a Master. The ritual, in this case, would be unnecessary, as it is only used to bring the spirits to this world and tie them to their initial Master; cards sold in shops that have been purchased by shop owners from other mages are thus, easy to wield for newer users.

Virago Spirit Cards are notably far more durable than traditional cards; spilling such things as ink and water traditionally slip right off, leaving the card as good as new. However, destroying the card, which can be done through magic or ripping, will kill the Spirit, obviously severing their link to their Master.

Generic Spells
Summon Virago Spirit: Unrelated to the initial summoning ritual, this refers to the act of summoning a Virago Spirit forth from its card. While they are traditionally used for battle, a Virago Spirit will heed any order given by the Master for the duration of their Summon, and as such, can be used for a variety of tasks. Unlike Celestial Spirits, which require a mutual agreement from both the summoner and the spirit to reverse the summoning, a Virago Spirit will heed the order to return to their card if it is issued from their Master; recognized as the current Card Holder. Thus, while they can still be controlled by Doll Attack, sending them back into their cards to prevent them killing their Master is a simple matter.
 * Multiple Summons: As they are cards that resemble a game, multiple Virago Spirits can be used at once; the limit is set to the user's magical power. On average, summoning a total of three at any time is severely draining on the average user, while stronger mages can summon multiple cards.
 * Combination Attacks: Multiple Spirits working in unison can combine their magic for greater or even unique effects. A Virago Spirit is also capable of working in tandem with their Master, to combine their magical energies and enhance the power of each others spells, and even perform spells they normally could not on their own.

Advanced Spells
Fusion: A Virago Spirit's most useful ability is the ability of Fusion, or the ability to combine with more than one card to gain power. The Virago method of fusion is uniqued and varied, contrasting well with the Celestial Spirit's method; the Celestial Cross Fuse (星歌・一心同体 (セレスチアル・クロス・ヒューズ), Seresutiaru Kurosu Hyūzu lit. Celestial Elegy: Two Hearts Beating As One) and Spirit Convergence (スピリット・コンバージェンス, Supiritto Konbājensu). All forms of Fusion are permanent; they cannot be reversed, and as such, it is wise for Virago Spirit Mages, especially those with sentimental attachment to their cards, to think carefully when performing a Fusion.
 * Assimilation (融合 Yūgō): The first method of Virago Spirit Fusion, assimilation is exactly as the name implies; one card, serving as the base, absorbs the souls of one or more cards, as selected by their Master. This process is irreversible, and when it is completed, the host card remains, while the other cards crumble and fade into the wind. This method of fusion grants the host card a new level of power, absorbing the experience and battle strength of the previous cards, however, it is not a true fusion as the card makes no physical changes, nor does it gain new skills. Assimilation is viewed as horrifying by some, as it shows just how far a Virago Spirit will go to serve as its Master's weapon; giving up the limited individuality they have for an enhancement in power.
 * Ascension (超越 Chōzetsu): The second form of Virago Spirit Fusion, and truer to the general concept of what 'Fusion' means; Ascension is when a user merges two copies of the same card to create an enhanced version. Unlike Assimilation, which can be done with multiple cards, Ascension is set to two, no more, mo less, and the end result is a Spirit that bears great physical resemblance to their previous forms, but with several superficial changes; clothing, eye colour, etc, and their abilities are also magnified in power. Ascension, just like Assimilation, is the act of giving up one's individuality to become stronger, however, because both cards are the same, there is no true soul that is "lost" as both merely result in an upgraded form.
 * Amalgamation (合同 Gōdō): The third, and final variation of the Virago Spirit Fusion, Amalgamation is also referred to as True Fusion (純粋融合 Jungō). Amalgamation is the act of taking two separate, unrelated cards, and combining them to form a completely new individual. The act of legitimate fusion, the resulting card is a completely new individual, and may or may not bear any resemblance to its previous forms, as the resulting woman may possess a variety of different features that the former cards did not possess, from a change in skin tone to an apparent regression in age. The new card does, however, retain both the memories and personalities of either card, and the concept of the final result will usually be related to the class of the other cards; a priestess and a cleric, for example, would fuse to create a bishop. Amalgamation is the ultimate loss of individuality, as nothing of the original two Spirits remain when the fused body is created; only memories and the ghost of their former personalities. The power enhancement from this form of fusion, however is ultimately greater than the previous two.

Forbidden Spells
Overthrow the Empress (転覆后, Tenpuku Kisaki): A forbidden spell, classified as "Dark Magic" due to its nature, it is a Virago Spirit spell devised centuries ago by the most corrupt of minds; a conversion spell designed to take female souls, and seal them directly into a specially crafted card. Similar to the Human Subjugation Magic in its effect, this spell works on a female of any species, sealing their soul directly into a Virago Spirit Card, essentially turning them into a Virago Spirit that can be summoned at their beck and call. Retaining all of their abilities, they abide by the laws that govern Vigaro Spirits, and as such cannot disobey an order given by their Master; essentially making this a form of mind control. As with true Vigaro Spirits, these Spirits can undergo any variety of fusion, losing their individuality to the fused form that results. The one ray of light that exists for those trapped in this manner is the destruction of their card; while such an act killed traditional Spirits, a Subjugated Spirit will be set free, and return to their normal form, should their card be destroyed. The trapped individual cannot be restored, however, if their soul is fused into another Spirit.

Trivia

 * Viagro Magic is based on the concept introduced in the game, Valkyrie Crusade, and thus employs similar mechanics.
 * Originally, the Celestial Spirit Mages were supposed to summon their spirits through cards, as opposed to keys; Hiro decided this idea was overdone, and opted to use keys as the method for summoning. Darkrai was more than happy to twist this concept for his own usage.
 * Virago is a woman who demonstrates exemplary and heroic qualities. The word comes from the Latin word vir, meaning 'man' (cf. virile) to which the suffix -ago is added, a suffix that effectively re-genders the word to be female.