Demons are types of units with a number of properties. They require undead leadership, but are not subject to the Banishment line of holy spells. They are also unaffected by a number of other undead-only counters, such as Dust to Dust and Wither Bones. Instead, they have some of their own counters.
Non-national spells which counter demons are:
A number of items also have significant bonuses versus demons. These include: