Oh, plenty of things! Spirit attraction flags that can draw entities toward the user, a compass that can direct you toward ghouls and other creatures, songs that pass directives to the undead...

[Also a bunch of actual curses and other various blood arts-y type nonsense but she doesn't need to know that... Though he leans forward a little with a tiny twinkle in his demon eye almost conspiratorially, and adds:]

They gave me so much trouble for being unorthodox but used my inventions so readily! That just attests to their usefulness, I guess.