I think a debating stage for a certain topic in the Harry Potter world could help people in the server share their opinions or ideas in the server to others. I have heard it has been a thing before, but got a little wild. I think it could work, as long as there are moderators in the stage, to make sure it doesn't get too rowdy again.
It could be weekly, with every stage having a different debate topic. Or maybe it could just be a one time thing. Nonetheless, however it's done. it's not any fun to completely avoid letting people express their opinions and attempt to convince others of it. Debating is not inheritably a bad thing, and if done right, it could make the server a bit more lively 
I think it should be a stage, so people who aren't necessarily participating in the main talking part of the stage, could say what they think in stage chat.