DnD homebrewing and campaign designing

Hey guys! I've been trying to work on some homebrew content for an idea of mine, it's gonna be very loosely horror based with plenty of room to goof off, but I also intend to mess around with and test alignments quite a bit with this campaign. I'm already working on a weapon that interacts with the choices the players make while using it (potentially cursing them if they become too evil), but I wondered if you guys had any other ideas on how to mess with or test alignment in a campaign. The thing with the weapon is that it can only really affect one person. I want to figure out a few more ways to mess with the others.