Awesome set of paper minis! The witches and bats would work very well in a Ravenloft/Curse of Strahd adventure or campaign. The witches would also work well as hags in any fantasy rpg. I haven't used the witches yet in my own 5E campaign, but have used the bat swarm and giant bats in a Halloween adventure. You can see pictures and read the write-up of the adventure here: https://thulaen.wordpress.com/2017/09/01/s- ession-6-grim-manor-part-ii/