What do you use to kill a demon???

In many cultures there are thousands of different types of demons. Some of the common methods of killing them are silver and decapitation.

Well let see, from the fantasy books I have read - They don’ t like crosses or holy water. Some of the fantasy books have it that you can’t truly kill a demon, only destroy its corporeal (physical) form - which banishes back to hell. Usually say after the the demon’s corporeal form has received enough physical damage to it the demon will abandon it b/c it takes too much effort to keep it together.

so those are some common ideas I have seen in fantasy books. Although its your book, so you can bend and tweak those rules to fit your universe. I have seen lots of variations on those ideas

You can’t kill a spiritual being.

reflected sunlight from a cross! or a tapering three-edged spiked Bayonet.

vampire a steak in teh heart

The most commen ways are to decapitate it, burn it, or get an exorcism.