First, the Sunbane. As the companions approach Mount Thunder through the eastern borderlands of Andelain, the desert sun rises, tearing ghastly rents in the fraying fabric of the Land's last surviving Law:
For Covenant and his companions, there is no longer any defence, any veil between them and their doom in Lord Foul's demesne. Linden is still appalled by the accusation of Dead Lord Kevin, that Covenant intended to give his ring to the Despiser. The Giants' enormous strength is failing, fraying: the First feels naked and effectless, measuring the futility of a single sword against the Despiser and all his minions; Pitchwife, stricken beyond bearing at his wife's extremity as well as his own, snaps his flute in two and hurls it across the dying landscape. Findail, too, has come to the point of his own crisis, and his denials of Vain's dark purpose take on a petulant and perfunctory tone.The Hills still clung to the life which made them lovely. While it lasted, Caer-Caveral's nurture had been complete and fundamental. The Sunbane could not simply flush all Earthpower from the ground in so few days. But the dusty sunlight reaching past the shoulder of Mount Thunder revealed that around the fringes of Andelain — and in places across its heart — the damage was already severe.
The vegetation of those regions had been ripped up, riven, effaced by hideous eruptions. Their ground was cratered and pitted like the ravages of an immedicable disease. The previous day, the remnants of those woods had been overgrown and strangled by the Sunbane's feral fecundity. But now, as the sun advanced on that verdure, every green and living thing slumped into viscid sludge which the desert drank away.
But it is Covenant who suffers worst of all, for he knows that in the end, all these dooms are on his head:
But in his suffering, he has learned to distinguish himself from the Despiser, his own essential qualities from Foul's; he has regained the paradox of white gold that enabled him to confront Despite the first time."It's not my fault," he went on harshly. "I didn't do any of this. None of it. But I'm the cause. Even when I don't do anything. It's all being done because of me. So I won't have any choice. Just by being alive, I break everything I love."
Just as the Quest for the Staff of Law did in LFB, all those thousands of years (and pages) ago, once more Covenant and his companions pass down Treacher's Gorge into Mount Thunder to confront the doom of their age. But this time there are no Lords to guide the way, no Staff of Law (as far as they know) awaiting them at quest's end; just a funeral march towards what looks like certain defeat in the Despiser's new abode. In such circumstances, words like stealth and caution are virtually without meaning:"No!" the First protested. . . . "This price will be exacted from him if you do not doubt!"
. . . .
"That's wrong." [Covenant] spoke softly, in threat or appeal. "You need to doubt. Certainty is terrible. Let Foul have it. Doubt makes you human."
As they enter Mount Thunder, Linden struggles with herself, her desperate yearning for power against her visceral horror of possession:The First scanned the thrashing River, the increasing constriction of the precipitate walls, then raised her voice through the roar. "Earthfriend, you have said that the passages of this mountain are a maze! How then may we discover the lurking place of the Despiser?"
"We won't have to!" His shout sounded feverish. He looked as tense and strict and avid as when Linden had first met him — when he had slammed the door of his house against her. "Once we get in there, all we have to do is wander around until we run into his defenses. He'll take care of the rest. The only trick is to stay alive until we get to him!"
Scant paces inside the tunnel, Findail makes a fresh attempt upon Vain's life, hurling him from the road into Treacher's Gorge. Confronted by Linden, he confesses that what passes for conscience in the Elohim leaves him no other defence against Vain's purpose than to attack Vain himself:Out of daylight into the black catacombs, where so much power lurked and hungered.
Where no one else would be able to see what happened when the outer dark met the blackness within her and took possession.
She fought the logic of that outcome, wrestled to believe that she would find some other answer. But Covenant intended to give Lord Foul his ring. Where else could she find the force to stop him?
But Vain survives, of course — a mere fall into a fathomless abyss is hardly enough to faze the incarnate form of the ur-Viles' understanding of Law — and when the company reaches Warrenbridge, he is already on the other side, having slain the Cavewight guards. But the alarm has been sounded against them, and their capture will be only a matter of time. Linden offers to lead the way to the Despiser, using her percipience to guide her towards him, but she is not yet near enough; not even her senses can make out his presence through miles of mountain rock. Reluctantly, she acquiesces as Covenant chooses to follow Findail's lead.He was ashamed of what he had done to Vain — and determined not to regret it. "You have taught me to esteem you. You bear the outcome of the Earth well. But my peril is thereby increased.
"I will not suffer that cost."
Now it is Covenant's turn to rehearse his final struggle: the acceptance of his own death. Until now his physical condition has been far different from that of his body in the 'real' world; against all reason, Linden has even dared hope that he would find a way to survive, or that she could find one for him. But now, taking a fatal and deliberate step towards his doom, he shaves off the beard he has grown since he was summoned to the Land.
Wise words, indeed. For by now, Covenant knows he has no hope of surviving any of his possible risks, whether he chooses them or not. He will meet his doom head-on, with his eyes open."I did this the last time I was here. An ur-vile knocked me off a ledge. Away from everyone else. I was alone. So scared I couldn't even scream. But shaving helped. . . . It takes the place of courage."
. . . . "I don't like it." His purpose was in his voice, as hard and certain as his ring. "But it's better to choose your own risks. Instead of just trying to survive the ones you can't get out of."
As they near the heart of the Wightwarrens, Linden faces another temptation in the dark, stronger and more evil than any she has yet endured. They are passing by a cavern used by the Cavewights as a charnal pit:
Passing down a Cavewight roadway hewn through the rock, they come to the rim of a gulf, a lake of magma at the bottom. This is where the Demondim cast their failed breeding experiments to be destroyed; this is where Findail makes his last desperate attempt to destroy Vain. Taking the form of a Sandgorgon, he knocks Vain off the rim into the gulf, but falls with him. In a scene reminiscent of the wizards' duel from The Sword and the Stone, Findail changes into one form after another, trying to escape the fall and break free of Vain's grip. In the end he fails to break free; both Vain and Findail are caught in a spout of lava and sucked down into the lake of fire.The fetor called out to her like the Sunbane, urged her to surrender to it — surrender to the darkness which lurked hungrily within her. . . . If she let go now, she would be as strong as a Raver before she hit bottom; and then no ordinary death could touch her. Yet she clung to the rough treads with her hands, thrust at them with her legs. Covenant was above her. Perhaps she was already safe. And she had learned how to be stubborn.
Apparently, Vain has been destroyed. But as he nears the place of his making and his destiny, he has already begun to take on the strange power for which the ur-viles designed him:
(Emphasis mine.)After all this time and distance and peril, he was lost before he found what he sought. Before she understood —
He had gripped Findail with the hand that hung from his wooden forearm.
With this line, Donaldson foreshadows Vain's eventual survival and the triumph of his purpose; yet he deprives his characters of that hope, leaving them to confront their individual destinies with their own unaided strength. This is a master-stroke of plotting.
But the delay has been costly. While Vain and Findail fought, and the others looked on, a band of Cavewights came upon them. They flee into a side passage, split up, and lose one another for vital moments before converging in a tunnel full of the gangrel creatures. Covenant tries in vain to deflect the peril from his friends by offering himself up as a prisoner or hostage; but the Cavewights' indiscriminate malice will not accept one victim, even the most valuable, when they can capture all four.
At the crucial moment, Linden's old paralysis has come back one last time to defeat her, with the timely help of a Cavewight's fist. Like Vain and Findail, like Covenant himself, she has apparently failed at the last test, and the triumph of the Despiser is assured.The Cavewights surrounded him. They did not use their cudgels or axes: apparently, they wanted him alive. With their fists, they beat him until he fell.
Linden tried to reach him. She was avid for power, futile without it. . . . Wildly, she groped for Covenant's ring with her health-sense, tried to take hold of it. . . . Vain and Findail had fallen. The First and Pitchwife were lost. Covenant lay like a sacrifice on the stone. She had nothing left.
She was still groping when a blow came down gleefully on the bone behind her left ear. At once, the world turned over and sprawled into darkness.
But only apparently.
For in the tests they have endured, she and Covenant have learned their final lessons. Because they fought to the last with all their power and cunning, all their rectitude and their love for the Land, they have learned how to remain themselves when they are at last brought before the Despiser as prisoners. Without this bitter defeat, the final victory might not have been possible.
In this chapter as the company journeys into the maze of Mount Thunder, I put myself in Linden's shoes. I thought what if my husband, my love, knew he the moment he would die and each moment that passed was one moment closer to that realization. I would hope against hope for a miracle that at the last minute he would be saved and stay with me, but deep down inside I would know that death was inevitable. And the last precious moments would not be spent wrapped in each other's embrace, but confronting the most horrifying evil. And then you wonder how will you go on when your love is gone, after you have been forged into one being. How do you separate yourself from that love? A part of you would have to die as well. 
