A few weeks ago, the group I was with was playing through the Ravenloft campaign using both Dungeons and Dragons, 3.5 Edition with hints of Eberron thrown in. Our party was a decent size and had all kinds of character classes available. I was a gnome wizard and a psion had just recently joined. She told us where to find a group of witches we needed to locate in order to find an artifact that could help us defeat a powerful vampire that had been terrorizing the land. When we found the thireen witches, they were performing a ceremony to summon a high level demon. Since there were so many we decided to strategize.
We had a bard in our party and just to prove how useful he could be, we decided to coordinate our ideas. He would cast major image to create the illusion of a red dragon swooping down on the witches. The two of us were off at a decent distance where they couldn't see us. When the dragon "breathed fire" at the witches, I immediately cast fireball on them to make the illusion even more convincing. The results were hilarious as I rolled good damage. Six of the witches were dead, and one was scorched beyond belief, but she successfully rolled her will save to disbelieve that the dragon was real. So this witch just looks up at this dragon that apparently fried a good amount of her convent, being herself burned to a crisp and the first words out of her mouth were "that dragon isn't real." Let's just say the remaining witches had a huge penalty to their own will saves and weren't convinced by their fellow witch. The rest of the party handled the remaining witches with no problem.