Every story needs a villain. In the fantasy world, there have been helpful wizards (think Gandolf), but most often, evil ones. Helpful wizards don’t always turn out to be all that helpful. They intend to do well, but things go wrong. Instead of starting a warming fire, they set the forest ablaze. Or what should have been a nourishing drink turns out to make someone very ill.
We all expect the evil wizard to cause harm, so it might be a huge surprise if the wizard actually does something kind.
Your task is to write a story in which everyone suspects the wizard. Begin with the event. What happened, how did the wizard get involved, how do the people feel, and what is the eventual result?
Is the wizard the main character or someone else? Is the wizard friend or foe? Where does the story take place? Castle? Forest? Mountain top?
Are there a lot of people nearby or is the location remote?
Lots of decisions to make, keeping in mind that readers want tension. On top of that, keep in mind that tone impacts the story as well. If you write a comedic story, the overall tone is completely different if terror and damage occur.
Have fun with this one.