Zodiacs

The Twelve Zodiacs are a group of powerful Spirits created from their respective constellations by Shura's human cards.

They can duel using a unique skill similar to the concept of Deck Masters, where their own effects apply from the start and they can be brought to the field at any given time. With their unique dueling style and cards, these spirits duel very distinctively and become powerful threats in the war for the Ka.

UPDATE: This idea can be recycled in "Five" by making one of the professor's heirs split their Code Card into 13 or 14 cards, with their allies each bearing one of the Zodiac Cards and acting as their guardians. If they are caught inside the game, each Zodiac could be a "firewall" that can only be torn down by defeating them in the game.

Taurus
Taurus uses a Raging Bull Deck.

Taurus can attack on the first turn. During battle, it becomes unaffected by any effects, also, its attack cannot be negated or prevented. Furthermore, each time it attacks, its ATK increases.

He uses these abilities with effects that enable multiple attacks and skip to Battle Phases to gain momentum and make its power even more terrifying.

Gemini
Gemini uses a Mirror Deck.

His opponents find it weird that Gemini is a lone monster. However, the mystery lies behind his effect.

At any given time, Gemini can become a perfect copy of another monster on the field. Furthermore, he can swap around effects and attacks to another identical monster, making it so that he can redirect harmful effects and attacks to his "twin", as well as redirect beneficial effects that would affect the opponent's monster to himself.

Gemini includes effects that let him bring out powerful opponent monsters to copy, as well as counter cards for mirror matches.

Cancer
Cancer uses a Demise Deck.

His effect sends all other cards on the field to the Graveyard at the end of each turn. Furthermore, he gains protection for each card sent to the Graveyard.

Cancer uses this skill alongside cards with Graveyard effects, reflecting the myth of cancer, who was crushed by Hercules but then Juno exalted it to the sky. His other cards also shine after being "crushed" and sent to the Graveyard.

Leo
Leo uses a King's Deck.

Leo is meant to rule all beasts, so he cannot be destroyed by another monster's attack or effect. Furthermore, each time a monster battles Leo, or attempts to use its effect on him, Leo gains that monster's effects as well.

Leo uses an array of anti-backrow cards to cover his weakness.

Virgo
Virgo uses a Noble Deck.

The Virgo must remain pure, so she cannot attack or be attacked. Furthermore, while she's in play, no cards can be destroyed.

Virgo uses this effect with noble warriors who are willing to sacrifice themselves on battle. They achieve immense strength in exchange for their self-destruction, however, the noble virgo protects them.

Libra
Libra uses a Burning Scales Deck.

With Libra's effect, each time a card is played on the field, an identical Token is played on the opponent's field. Furthermore, if a player loses a card on the field, their opponent also loses 1 card of the same type, so that both players always control the same number of cards.

Libra takes advantage of this effect to get rid of his own cards while burning the opponent for it, getting rid of the opponent's cards as well in the process.

Scorpio
Scorpio uses a Poison Deck. He goes first and uses monsters that skip the turns, allowing him to attack directly with Scorpio right away.

Despite only having 1 ATK point, if Scorpio inflicts damage to the opponent, its effects trigger after each turn, crippling the opponent until the poison ends them.

Scorpio's monsters mostly have effects revolving around skipping forward, making the "venom" spread quickly and cripple the opponent so they can't do anything.

Sagittarius
Sagittarius uses a Pinpoint Hunt Deck.

Sagittarius' arrow can destroy all copies of a card once every turn, no matter where they are - in the opponent's field, hand, Deck or Extra Deck. This effect allows him to quickly cripple his opponent by hunting and destroying their key cards ASAP, while his other Centaurus monsters help slow the opponent down and pressure them.

Capricorn
Capricorn uses a Wisdom Deck.

His effect allows him to manipulate cards in different ways, but he can only use one ability at a time: ● Choose the card your opponent will draw ● Choose the targets of your opponent's effects and attacks ● [...]

While his Deck lacks actual fighting power, it's a highly disruptive Deck that becomes tricky to face with one's regular tactics.

Aquarius
Aquarius uses a Heaven's Aquarium Deck.

While in play, the water bearer creates a field of water where divine sea creatures may be Summoned forth. Aquarius' presence not only Summons those powerful monsters, but also creates a field where the opponent cannot move freely.

Ophiuchus
While not revealed at first, the serpent bearer is the secret 13th Zodiac, and a very important part of Shura's plan.