Kevin Landwaster was the last of the Old High Lords of Revelstone, being the son of Loric Vilesilencer, grandson of Damelon Giantfriend, and great-grandson of Berek Halfhand. He gave his name to Kevin's Watch.
As his title implies, he is remembered for giving into despair and enacting the Ritual of Desecration in a futile attempt to defeat Lord Foul, destroying the Land in the process. Despite him having died long before the events of even the first book, Lord Foul's Bane, Kevin's actions serve as a reminder as to what happens when one gives into despite, and thus lead the New Lords to make the Oath of Peace.
Even in death, Kevin is beset by tragedy; his later summoning by Elena in The Illearth War breaks the Law of Death, which has massive consequences that follow well into the Second Chronicles. His grief is never forgotten, and four thousand years later he informs Linden Avery of Thomas Covenant's intentions in White Gold Wielder.
In the course of a life that lasted a thousand years, Kevin succeeded his father Loric as High Lord.
A major moment of his tenure occurred when an army of Haruchai entered the Land through Guards Gap, intent on conquest. Instead, they were overwhelmed by the sight of Revelstone and the might of High Lord Kevin and the Staff of Law. The Haruchai swore a Vow to serve the Council of Lords; five hundred of them became the Bloodguard, warders of the Lords and Lord's Keep, losing the ability to sleep or age.
Later, Lord Foul assumed a mortal guise to gain admittance to the Council. He feigned friendship with the Council's members and was accepted by Kevin, who taught him a great deal of his secret lore. However, Foul was unable to conceal all trace of his malice and Kevin started to become suspicious of him.
Seeking to disrupt the Council, Foul set a trap for Kevin near Mount Thunder, but Kevin--mistrustful of Foul's intentions--sent a delegation of Lords in his stead. They were butchered at the spot known thereafter as Treacher's Gorge.
Now openly enemies, Lord Foul set about corrupting the southeast regions of the Land, making them into the Spoiled Plains and Shattered Hills around his own lair: Foul's Crèche. Kevin was unable to perceive what Foul was doing in the despoiled region; in truth, Foul had begun breeding monstrous creatures to be his servants and warriors, then started a series of internecine wars against the Lord's Council. All of this resulted in widespread death and destruction.
Sick of the butchery and seeing no respite for the Land or its peoples, High Lord Kevin created the Seven Wards--a systematic, cumulative store of his knowledge--and gave the First to the Giants, who departed the Land by sea. He sent the Bloodguard to safety in the mountains and attempted to preserve as many innocents as possible before facing Lord Foul and enacting the Ritual of Desecration. Kevin believed that the Ritual would obliterate Foul, even at the cost of ruining the Land for a thousand years.
Foul accepted Kevin's invitation, and together they enacted the Ritual. To Foul's surprise, it did destroy Foul's physical form (something he never regained). However, the effects on the Land were brutal: people, animals, plants were destroyed and the Land left nearly uninhabitable for an age afterward. In the instant before his death, High Lord Kevin realized that Lord Foul and the Ravers could not be slain by Desecration; Foul's existence is more fundamental than even the Arch of Time and no power within the Arch can unmake him. Kevin dies howling in agony at comprehending the vastness of his folly.