It's obvious that Donaldson was cutting his teeth, so to speak, while writing Lord Foul's Bane. To be certain, that book had periods of brilliance, such as the occurrences in Andelain, but all in all it was probably the weakest book in the series. (That doesn't mean it isn't good - just that the rest of the books are incredible.)
In The Illearth War Covenant is called back to the Land for a second time, and his image of a reluctant hero is burnished in our mind even more than it was in the previous book, for while he was being summoned he was also on the phone with his ex-wife, Joan. The woman who left him for fear of his leprosy, the woman with whom he was still in love, the woman who was telling him, right then, that she missed and needed him. So he protests his summoning vehemently, but to no avail. As the new High Lord Elena indicates, they have no knowledge of how to send a person back once a summons is complete.
The Council of Lords has some new faces on it. It's been forty years since Covenant has been to the Land, and seven years (seven "Land" years) remain until the fulfillment of Foul's ominous prophecy from Lord Foul's Bane. The Lords are desperate. While they regained the Staff of Law and found High Lord Kevin's Second Ward at the end of Lord Foul's Bane, they have learned very little. The language, they find, is difficult to penetrate, and they find themselves unequal to the task of mastering the lore. Due to their sense of overwhelming failure and inadequacy, and other baleful events, they make the decision to summon Covenant.
There is another addition to Revelstone: Hile Troy. He is a character from the "real world", someone who has read (or had read to him) Covenant's best selling novel. This is, perhaps, Donaldson's way of telling us that Covenant's experiences most definitely is not a dream (which Covenant is still convincing himself of). He's also blind, and unlike Covenant - who maintains fierce unbelief - Troy believes in the Land with a passion that precludes life.
Many readers interpret Troy's character as what Covenant *should* be. If Hile Troy had a white gold ring, his passion, his love for the land (for it allowed him to see again - and besides, everyone, even the readers, fall in love with the Land) would lead him directly to a confrontation to Foul. Unfortunately, not understanding the dilemmas of power, he would likely experience a resounding defeat. What people don't understand about Covenant, and Troy's character is supposed to help them understand this, is that Covenant's stubborn unbelief exists for a reason. In Lord Foul's Bane, Donaldson meticulously discussed the rigors of leprosy, what it meant to be a leper, what it meant to *survive* as a leper. And though bitter and angry at life and everything around him - or perhaps because of his bitterness - Covenant made the decision to live. And living entails never, ever letting your guard drop for one second. Because if you do, you can bump into something, not realize that you're bleeding internally, and die of hemorrhaging; gangrene can set in; and much more. So Covenant's unbelief, while incredibly frustrating, is completely understandable. He needs to believe that the Land isn't real, because if he gives in to it, then when he wakes up from his dream (for it may be a dream), his guard may drop, and he could die.
So it's unfortunate that people don't recognize Troy for what he is, and see him for exactly the opposite of what Donaldson intended.
Other reviewers have said this is the best book in the series. I love this book, as it introduces some extremely intriguing relationships and concepts (Elena and Amok, the latter of which is the key to High Lord Kevin's Seventh Ward - talk about heightened anticipation), and the devastating fear that Foul has mastered the Illearth Stone to such a degree that he can cut chips off of it and give it to his servants (Ravers).
The battle of Garrotting Deep (yes, similar in placement and scope to the epic Battle of Helm's Deep in The Two Towers) shows that Donaldson, like Tolkien before him, can write both of beauty and of beauty's absence in the heart of darkness of war. He is quite adept at handling battle scenes.
Many second books suffer from the so-called sophomore slump. Not this one. I don't think Donaldson is capable of writing such a book, as The One Tree (the second book in The Second Chronicles of Thomas Covenant) is arguably the most intriguing of the series, and within that book in particular are the seeds for the Last Chronicles, which everyone - and I mean everyone - should read.