KingdomXathers

Predaplant Darklord's Breath
DARK/LINK-2/Plant/Link/Effect/1800 ATK/Link Arrows: Bottom-Left, Bottom-Right
2 Plant and/or Fairy monsters
This card is also always treated as a Fairy monster. You can use 1 monster with a Predator Counter(s) your opponent controls as Material for this card's Link Summon, regardless of its Type. You cannot Special Summon monsters from your Extra Deck while you control this card, except Fusion Monsters. Once per turn: You can discard 1 "Predap" or "Darklord" card from your hand, then target 1 "Predaplant" or "Darklord" monster in your GY; Special Summon it. (Quick Effect): You can pay 1000 LP, then target 1 "Polymerization", 1 "Fusion" Normal Spell/Trap, or 1 "Darklord" Spell/Trap in your GY;  apply that target's effect, then shuffle that target into the Deck. You can only use this effect of "Predaplant Darklord's Breath" once per turn.

Next: Gravekeeper’s + Vampire

I posted one of these before in Singles, but I figure it'd be better now to post more than one.  I may add more later, including erratas of the Anime-only cards.

For each of these I will list the card's corresponding story that it takes inspiration from, as well as what the card relates to in that story.

Raven Maiden

DARK/Lv 4/Winged Beast/Effect/1300 ATK/2000 DEF

“Golden Castle of Stromberg” in your Field Zone is unaffected by your opponent’s card effects. When this card is Summoned: shuffle all of your face-down banished cards into the Deck. When a card(s) is banished face-down: You can target 1 monster you control that specifically lists “Golden Castle of Stromberg” in its text; that target gains 500 ATK and DEF. Once per turn, during your Main Phase: You can shuffle 5 of your top-most face-down banished cards into your Deck.

(Comes from "The Raven", the same story that "Golden Castle of Stromberg" also hails from.  A princess who was cursed to become a raven, she hopes for someone to deliver her from her curse.  The Golden Castle of Stromberg is her residence.)

Invisible Horseman

LIGHT/Lv 4/Warrior/Effect/300 ATK/1000 DEF

If you control "Raven Maiden", you can Special Summon this card (from your hand). You can only Special Summon 1 "Invisible Horseman" this way per turn. Gains 100 ATK and DEF for each of your face-down banished cards. When this card inflicts Battle Damage to your opponent: You can shuffle up to 3 of your top-most face-down banished cards into your Deck. While “Golden Castle of Stromberg” is on the field, this card can attack your opponent directly, also, if this card attacks, your opponent cannot activate Spell/Trap cards or their effects until the end of the Damage Step.

("The Raven", once again.  The protagonist who attempts to deliver the Raven from her curse.  Near the end of the story he is armed with 3 items that he tricked a trio of robbers into giving him: a stick that can open any door that it strikes, a cloak of invisibility, and a horse that can climb any surface--including the slippery glass mountain upon which the Golden Castle rests.)

The Giant Brothers’ Maps

Normal Spell

Banish 1 card from your Deck that specifically lists the card “Golden Castle of Stromberg” in its text, except “The Giant Brothers’ Maps”. During your next Standby Phase after this card’s activation, add that card to your hand. You can only activate 1 "The Giant Brothers' Maps" per turn.

(Again, "The Raven".  The previously mentioned protagonist acquires assistance from a pair of giants after feeding them a loaf of bread, a slab of meat, and a bottle of wine, all of which would never run out.  The maps in question are used to help the protagonist locate the Golden Castle of Stromberg.)

Bearskin

EARTH/Lv 7/Beast-Warrior/Effect/2800 ATK/2100 DEF

Cannot be Normal Summoned/Set. You can Special Summon this card (from your hand) by shuffling 7 of your top-most face-down banished cards into your Deck. You can only Special Summon 1 “Bearskin” this way per turn. You can only control 1 face-up “Bearskin”. Once per turn, you can reveal 3 cards from your Deck that specifically list the card “Golden Castle of Stromberg” in their text, your opponent randomly picks 1 for you to add to your hand, and you banish the rest, face-down. If this card has been face-up and in your possession for at least 4 of your turns consecutively without control of it being switched, this card becomes unaffected by your opponent’s card effects. After your 7th consecutive turn that this face-up card has been in your possession without control of it being switched, you win the Duel.

(From the story of the same name.  The titular character was a soldier who had lost everything after a war, and ends up making a deal with the Devil: in exchange for being given a coat with pockets containing limitless gold and a bearskin that he must sleep in--thus earning his new name--Bearskin must survive for seven years without praying, bathing, or trimming his hair or nails.  Should he survive the seven years, Bearskin would keep the wealth in the coat's pockets and be freed, but should he die before then, the Devil would claim his soul. During his fourth year, Bearskin helps a man in desperate need, and as a reward the man promised to let Bearskin marry one of his three daughters.  The two eldest daughters rejected Bearskin due to his revolting visage, while the youngest daughter agreed to fulfill her father's promise.  Once Bearskin survived the seven years, the Devil cleaned Bearskin up 'til he was good as new, and Bearskin married the youngest daughter shortly after, while her older sisters, enraged over realizing what they had passed up, committed suicide, earning the Devil 2 souls for the price of one.)

Glife’s Beloved

WIND/Lv 3/Winged Beast/Effect/1200 ATK/1200 DEF

If this card is Normal or Special Summoned: You can Special Summon 1 “Glife the Phantom Bird” from your hand or GY. If a card(s) on the field is destroyed by a card effect: You can reveal 3 of your top-most face-down banished cards, then if at least 1 of those cards specifically lists the card “Golden Castle of Stromberg” in their text, add one of them to your hand and send the rest to the GY, otherwise the revealed cards remain banished, face-down. You can only use each effect of “Glife’s Beloved” once per turn.

(The wife of "Glife the Phantom Bird", both of whom come from "The Griffin".  The protagonist of that tale is tasked with fetching a feather from the griffin's tail.  Upon reaching the griffin's den, he met the Griffin's wife, who agreed to help him to not only acquire the tail feather, but also the answers to three questions he had been asked along the way.)

Jacob and Will, The Grimmwriters

DARK/LINK-2/Fairy/Link/1800 ATK/Link Arrows: Bottom-Left, Bottom-Right

2 monsters, including a monster that specifically lists the card “Golden Castle of Stromberg” in its text.
Cannot be targeted for attacks or by card effects, while you control another card that specifically lists the card “Golden Castle of Stromberg” in its text. If a card in your possession that specifically lists the card “Golden Castle of Stromberg” in its text destroys your opponent’s card(s) (by battle or effect), the destroyed card(s) is banished, face-down. During your Main Phase: You can Special Summon 1 monster from your hand that specifically lists the card “Golden Castle of Stromberg” in its text. You can only use this effect of “Jacob and Will, The Grimmwriters” once per turn.

(What else can I say for this one? This is based on Jacob and Wilhelm Grimm, the Brothers Grimm themselves.)

Sweet Tooth Siblings

LIGHT/Lv 3/Fairy/Effect/1000 ATK/1000 DEF

If this card is Normal or Special Summoned: You can add 1 “Gingerbread House” from your Deck or GY to your hand. If “Golden Castle of Stromberg” was in a Field Zone when you activated this effect, you can also add 1 card from your Deck to your hand that specifically lists the card “Golden Castle of Stromberg” in its text, except “Sweet Tooth Siblings”. You can only use this effect of “Sweet Tooth Siblings” once per turn.

(This is Hanzel and Gretel, if it wasn't too obvious from its primary effect.)

Gingerbread House

Continuous Spell

You can only control 1 face-up “Gingerbread House”. During each of your opponent’s Standby Phases: Target 1 monster your opponent controls; that target gains 600 ATK, then, if its ATK became 2500 or more by this card’s effect, destroy that target, and if you do, gain 500 LP. If “Golden Castle of Stromberg” is face-up in a Field Zone, this card’s effect is activated during both players’ Standby Phases, also, this card cannot be targeted or destroyed by card effects.

(Errata of the Anime's "Gingerbread House", made to better cooperate with the rest of the Deck.)

Raven Maiden

DARK/Lv 4/Winged Beast/Effect/1300 ATK/2000 DEF

“Golden Castle of Stromberg” in your Field Zone cannot be targeted or destroyed by your opponent’s card effects. When this card is Summoned: shuffle all of your face-down banished cards into the Deck. When a card(s) is banished face-down: This card gains 500 ATK and DEF. Once per turn, during your Main Phase: You can shuffle 5 of your top-most face-down banished cards into your Deck.

I designed this card to not only mitigate the cost of "Golden Castle of Stromberg" while supporting it, but also to add another representative from "The Raven", the same Brothers Grimm tale that "Golden Castle of Stromberg" originates from.

It's more like the "Maju" Series, which includes Gren Maju Da Eiza, but I'll give it a shot nonetheless.  Whoever goes next can feel free to critique these, if they desire to.

Chron Maju Da Xoza

WATER/Lv 6/Fiend/Effect/? ATK/? DEF

Cannot be Normal Summoned/Set. Must be Special Summoned either by a card effect while banished, OR by banishing 3 monsters from your hand or GY, and cannot be Special Summoned by other ways. This card’s ATK and DEF each become equal to the combined ATK of the 2 monsters with the highest ATK amongst banished monsters. When this card inflicts battle damage to your opponent; You can add 1 of your banished monsters to your hand, but for the rest of this turn you cannot activate cards, or the effects of cards, with the same name as the card added to your hand by this effect. This effect of “Chron Maju Da Xoza” can only be used once per turn.

Treacherous Maju Garzett

LIGHT/Lv 6/Fiend/Effect/? ATK/0 DEF

Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand) to your opponent’s side of the field by Tributing 1 monster they control. You cannot Normal Summon/Set monsters during the turn your Special Summoned this card, except Fiend “Maju” monsters with an original ATK of 0 or ?. You can only Special Summon 1 “Treacherous Maju Garzett” this way per turn. Cannot be used as Material, or Tributed, except for the Tribute Summon of a monster with an original ATK of 0 or ?. This card’s ATK becomes twice the original ATK of the monster Tributed for this card’s Special Summon. If this card would inflict battle damage to your opponent, your opponent instead gains LP equal to that same amount.

Warpdrive Maju Garzett

EARTH/Rank 6/Fiend/Xyz/Effect/? ATK/? DEF

2+ Level 6 monsters
You can also use Fiend “Maju” monsters of any Level as Xyz Materials for this card’s Xyz Summon. This card’s ATK and DEF become equal to the total Level of this card’s Xyz Materials x 200. When a monster(s) is Tributed; you can attach 1 of those monsters to this card as Xyz Material. After the Damage Step of a battle involving this card: Detach 1 Xyz Material from this card.

Advance of the Maju

Normal Spell

Activate while you control no monsters: Immediately after this card resolves, Tribute Summon 1 Level 5 or higher Fiend “Maju” monster with an original ATK of 0 or ? by Tributing from your Main Deck, a number of Fiend monsters needed to Tribute Summon that monster. During this turn, only that Tribute Summoned monster can attack, also, its current ATK is doubled. You can banish this card from your GY; add 1 Fiend “Maju” monster with an original ATK of 0 or ? from your Deck to your hand. You can only use each effect of “Advance of the Maju” once per turn.

Next Card(s): Expand "Man-Eater Bug" into an Archetype