> But it does not infringe on the copyright on any WotC property. It's not that simple. The main thing to remember is that even a threat of an expensive lawsui

> But it does not infringe on the copyright on any WotC property. It's not that simple. The main thing to remember is that even a threat of an expensive lawsuit is a pretty credible one in the US, because of how the system is set up. Yes, frivolous suits get thrown out pretty fast, but that's still not cheap (because you need to hire an attorney to communicate with the court on your behalf, because, again, the system is set up that way), and when it comes to copyright very few things are that clear cut. Just with a mod for a game it's easy to argue that without the game there's no mod, so the mod is a derivative work. And if your campaign is bolted to the mechanics, then it's not hard to argue that the campaign is basically genre-bending fanfiction (ie. copies the same themes into a new setting), so one might argue it should get the same legal treatment as a derivative work. Even if it's ~90% that you would win the case, it might cost you a lot, that's why this matters to businesses. (It likely doesn't matter to individuals or small clubs that publish things for free.)