Who is Darken Rahl from Wizard's First Rule and what is their importance?

Darken Rahl is the tall, muscular, blond villain bent on using his evil power to subjugate every creature in the three lands, the living as well as the underworld. He orders his men to slaughter the innocent villagers of Horner's Mill and to brutally rape the surviving women and children. He is scarred on the thighs and genital area from wizard fire wielded by Zedd when Rahl's father kills the wizard's wife.

Rahl is a practitioner of the negative subtractive magic, which can be used to destroy things. This is the equivalent of dark magic in Wizard's First Rule and gives him power over the underworld. Despite all of his flaws, Rahl is a very adept, powerful wizard. Only years of practice have given him the skill to carry out the elaborate incantations necessary to open the box of Orden. If he opens the right box, he will have additive as well as subtractive magic and rule the whole world.