Demon bosses are encountered as part of the Demon Flash MobsDistraction and Diversion. They serve as the main boss of the activity, although only one appears within each mob. It is protected by six imp heralds, four lesser demons and two black demons; the latter two it will devour to recover lost health. Its name and, to some degree, its appearance is random, but the prefix and suffix of its name will affect its abilities.
Attempting to use prayers excluding Protect Item while fighting the demon causes it to deal extra damage when hitting you. Using Blood spells will also heal the demon.
In order to receive a drop, the player must deal at least 500 damage to the demon boss in a single hit; once this condition is met a notification will be given to the player. The player must also stay in combat with the boss until it dies to be eligible for the rewards. If the player gets out of combat by any means, they will lose the ability to get the drop from the demon, and must deal 500 damage in a single hit again to be eligible for a drop.
Fighting a demon boss in the Wilderness will give different drops and a drastically increased drop rate for the demon slayer equipment. Demon slayer equipment will always be included as a secondary drop, similar to clue scrolls and effigies.