Undead
Undead are creatures animated through negative energy, as opposed to living beings who are animated by positive energy, or outsiders who are animated by the primal forces of the elements. Classic examples include skeletons, vampires, and ghosts.
Undead are generally classified into two categories: mindless and intelligent. Mindless undead, such as skeletons and zombies, only do what their masters tell them to do, or go on crazed, murderous rampages. Intelligent undead on the other hand, such as vampires and liches, are usually able to scheme and plot for centuries, snaring the living denizens of the world in plans within plans.
Turning Undead
Since clerics have such strong ties to positive and negative energy (through their healing spells and whatnot), they are also well-equipped to handle undead monsters. This usually takes the form of a cleric turning undead. When a cleric turns undead, he channels the power of the positive energy plane through his holy symbol, and causes any undead creatures nearby to flee or be outright destroyed. Priests of Good-aligned gods, such as Pengarond of Corellon Larethian, are able to do this.
Some clerics have stronger ties to the negative energy plane, though, and instead of causing undead creatures to flee, they cause them to cower in awe of the cleric's supremacy. Sometimes, they can even cause weak undead to obey their commands this way. Priests who worship Evil-aligned gods, such as Gertrude of Wee Jas, for example, do this.
