These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Lord Foul is one of the most horrifically evil Dark Lords in fantasy, and proud of it. He's called "the Despiser" for a reason, namely that he holds every living thing that's not himself in purest contempt, and is perfectly willing to annihilate physical reality purely so he can escape from it. While he's waiting to accomplish that, he gets his jollies by causing smaller-scale apocalypses (the one in the Second Chronicles purely to screw with Covenant's head), driving people so far past the Despair Event Horizon that they become agents of their own destruction, and giving magnificent monologues about how much you suck compared to him. All of this without the slightest shred of remorse, by the way, and Word of God notes that while he's essentially the Anthropomorphic Personification of evil, don't think it absolves him of moral responsibility for his crimes- at least theoretically, Foul always had the option to choose to stop being the Despiser, but doing so never entered his head. Rather, after every defeat, he just examines what he did wrong so he can be even more evil next time around.
Foul's Co-Dragons, the three Ravers, are just as bad. They were originally three human brothers whose evil was so great it survived past the destruction of their physical bodies as incorporeal demons with a thing for possessing people. In addition to being willing accomplices in all of Foul's crimes (because they think that when he breaks free of the Land, they can ride his metaphysical coattails into godhood themselves), and sharing his gleeful, psychotic sadism, each Raver has racked up a number of atrocities of his own. Moksha Jehannum Fleshharrower and Samadhi Sheol Satansfist both did stints as Foul's head general, massacring countless innocents (and their own troops) and Samadhi (as Gibbon na'Mhoram) was the head of a Path of Inspiration that sacrificed countless lives while lying to the people of the Land that it would help reverse the After the End conditions of the Sunbane (when in fact it was just making it worse), while Moksha stalked Covenant over much of the Second Chronicles infecting him with venom in order to force him to use his ring at full power whether he wanted to or not (which could well have destroyed the world, which was the plan). Turiya Herem Kinslaughterer doesn't show up as often as his brothers, but commits probably the single most appalling atrocity in the entire Chronicles- committing the genocide of the Giants of Seareach. Singlehandedly. While they refused to fight back.
Heartwarming Moment: When creating the new Staff of Law, Linden takes a moment to help her friends.
With the Staff of Law and the white ring. Linden caressed the fatigue out of the First's limbs, restored her Giantish strength. The rupture in Pitchwife's lungs Linden effaced, healing his respiration. Then, so that she would be able to trust herself later, she unbent his spine, restructured the bones in a way that allowed him to stand straight, breathe normally.
In the first book, Thomas Covenant does something horrible, which firmly establishes that, unlike a typical fantasy protagonist, he is notThe Cape. He spends the rest of the first trilogy trying, painfully, to drag himself back out of the moral black hole he fell into. Covenant's behaviour lead to a kind of cascade effect whereby the majority of bad stuff that happens in the book, and a lot of the series, is a consequence. The same goes for a significant amount of Covenant's suffering. Basically, it haunted Covenant for the rest of the series. For instance, Lena gave birth to Covenant's child, who was not completely sane, and went on to break a chunk of reality (the Law of Death) and give the Big Bad access to infinite undead armies of anything, up to and including fossils.
Foul himself has an odd crossing, because it is entirely verbal before he has a chance to actually do anything. Just reading his rant to Covenant about how he is going to corrupt and destroy the Land and there is nothing anyone can do to stop him, culminating in the declaration that he will annihilate hope from the universe, puts you off on rooting for the guy for good. It all just cements Foul's rep as what Card-Carrying Villains want to be when they grow up.