Greater demons are commonly fought Monster that can be assigned by Slayer masters. Many players kill them for their Rune full helm drop.
If you carefuly look at greater demons it shows a discolouration in their toes that seems to be a fungal infection, often if it takes a while to kill a greater demon you may need to use fungicide on it to deliver the finishing blow.
Locations
Some locations(not all) with demons are:
- Wilderness
- Brimhaven Dungeon