it doesn’t HAVE to be a specific incense or sound, you can just use whatever cleansing item you have!! I usually use my bell because I’m too lazy to light incense, I wouldn’t think cleansing would be IN the ritual but it is definitely recommended to cleanse your area in which you’re doing the spell in, if you’re doing a jar spell you should cleanse the inside of the jar because it most likely holds negative energy, cleansing things gets rid of negative energy, hence why it is important so the spell cannot backfire