Demonic rankers did not refer to any particular kind.
Each ranker that practiced unconventional ranking techniques, spells, techniques, artifacts, etc that required them to kill anyone was called a demonic ranker. Demonic rankers could therefore be anyone or of any race.
The laws against demonic rankers and demon practices were strict. Kingdoms and empires used every means at their disposal to get rid of them. That's because the demonic rankers would often bring death and destruction to the regions they were active.
The most notorious demonic rankers had bounties placed on their heads. The bounty hunting missions were available to all rankers, whether they were part of any guild or not.
Some rankers made a living hunting demonic rankers. Just like the notorious demonic rankers, the bounty hunters who slayed them would also come in limelight from time to time.