Ravers are bodiless evil spirits with the ability to possess and control some lesser creatures, and most humans as well. Giants and Bloodguard are typically immune to this power, and there are no known instances of a Raver possessing a Ranyhyn. There are only three Ravers, ancient brothers who each have many names but are commonly called turiya Herem, samādhi Sheol, and moksha Jehannum. Their greatest hatred is reserved for the trees of the One Forest of old, and their loathing of the Earthpower and all good things has led them to become Lord Foul's willing servants. The Despiser is somehow able to enhance their abilities when he pleases, but can prevent them from possessing individuals he deems too powerful. (They were not allowed to possess Thomas Covenant, for instance, because his ring would make them too powerful for Lord Foul to control.) This possession can be, and in some cases needs to be, facilitated by some external power. In the 'Illearth War' the Ravers were only able to possess their giant 'hosts' when they worked in harmony with the power of the Illearth Stone. They often serve as leaders in Lord Foul's armies, or as spies among his enemies.
There names are:
The three Ravers are virtually immortal; not one of the three has ever been actually killed. However, although the Ravers are for all intents and purposes impossible to kill, it is possible to effectively slay them by ripping their souls apart. This was the fate of Samadhi Sheol (a.k.a Gibbon-Raver); when it attempted to possess the giant Honninscrave in Revelstone the giant proved to be too much for the Raver to handle and in the act of trying to possess the giant, became trapped in its body and was then "rent" by the Sandgorgon Nom. However Atiaran once mentioned to Thomas Covenant that the Ravers cannot die whilst Lord Foul still lives