One idea could be a prequel where we see how the characters were before Dorothy arrived in Oz. For example, exploring the Scarecrow's life in the field, alone and longing for a brain. Another could be a story where Dorothy returns to Oz as an adult and has to deal with new threats. Or perhaps a fanfiction where the Wicked Witch of the West was actually misunderstood and we see her side of the story.
In RWBY Wizard of Oz fanfiction, the semblances of the RWBY characters might interact in unique ways with the magic of Oz. Weiss's glyphs could combine with Oz's magic spells, creating new and powerful effects. And Blake's shadow clones could be used to outwit the tricky situations in Oz, like fooling the flying monkeys.
One idea could be that muggles discover a powerful magical artifact and try to use it against wizards, thinking it's some kind of advanced technology. This could spark the war as wizards see it as a threat to their secrecy and power.
One idea could be a wizard who uses magic to bring back characters from the dead in a way that completely alters the power dynamics in Westeros. For example, bringing back Ned Stark and having him lead an army of the resurrected against the White Walkers.
One interesting behind - the - scenes story is about the Tin Man's makeup. It was made of aluminum powder which was actually quite toxic to the actor. He had to endure it for the filming. Also, the dog that played Toto was paid more than some of the human actors in the Munchkin scenes.
One idea could be a wizard in the North discovers a long - lost magic spell that can control the weather. This would give the North an advantage in the war against the White Walkers. Another plot could involve the wizard forming an alliance with the Starks and using magic to help them reclaim Winterfell.
One plot idea could be Finn and Huntress Wizard going on a quest together. They might face various monsters and challenges, and during this journey, their relationship could develop further, like they start to understand each other's motives and fears better.
Perhaps a plot where the wizard king is from a different magical realm and comes to the Harry Potter universe. He has to adjust to the different magical customs here while also trying to solve a mystery that involves a powerful magical artifact that was lost long ago. This could involve him teaming up with Harry and his friends and teaching them some new magical techniques from his own realm.
One idea could be that the Royal Wizards have a secret society within Hogwarts that Harry discovers. They have ancient spells and knowledge that could help him in his fight against Voldemort.
A plot could also revolve around a character from the Muggle world who discovers they have wizarding blood later in life. They then have to adapt to the wizarding world, much like Harry did when he first found out he was a wizard. But this character could bring in a fresh perspective, having lived in the Muggle world for a long time and being more familiar with Muggle technology and culture.
One idea could be a crossover with Harry Potter. Imagine the wizards from Wizard101 going to Hogwarts and interacting with the students there. They could compare their different magic systems, like how spells are cast in Wizard101 compared to using wands in Harry Potter.