Chapter 14 of Cassandra Claire's HP opus "Draco Sinister" has the brief endnote, "Oggrings and skolks are from Tanith Lee's White Horse, Black Castle [sic]."
Tanith Lee is one of my favorite authors, but although she's incredibly talented and prolific, her books go out of print quickly; most of my collection is made up of used paperbacks from secondhand bookstores and eBay. They're difficult to find, and I don't have all of them. While I'm not in the flaming-pitchfork crowd wrt CC, I do like to encourage other people to read TL's books, even if that ends up adding to my competition in bidding wars, and I rather wish that CC had noted more specific textual overlaps beyond merely borrowing isolated words/names or general concepts.
The story CC refers to is in fact the novella "Prince on a White Horse", originally published in 1982. It was reprinted as the second half (pp 179-302) of Dark Castle, White Horse, NYC: Daw, 1986. Although the following passages are technically from PoaWH alone, I'm marking them according to the pagination in DCWH. Some overlaps are vaguer than others. The version of "Draco Sinister" I've checked is the one on Schnoogle.
[Later addendum: corrected the order of DS14 excerpts; added some preceding/subsequent lines from DCWH and the Draco PDFs to provide more context; color-coded some of the more complex examples.]
DS14: "'All right, then,' said Harry. 'Let's go.'
"It was sunset, and the sky was golden streaked with silver threads like the threads in a tapestry. Ginny sat by the fire that Ben had made that afternoon, shivering very slightly. It was autumn in the time they were in currently. In the distance, she could see many small campfires burning around an assortment of tents. Clouds like dark red roses scudded high across the amber sky. The air smelled of oncoming frost, and rather strongly of dragons."
DCWH p. 185: "'That's silly! Oh, no it isn't. I forgot.'
"It was dawn and the sky was gold, with clouds like huge red roses floating about in it. The Prince nervously stared to make sure they weren't actually roses, but they were clouds all right."
DCWH p. 281: "They were in the sky, and the sky was golden streaked with silver thread like a tapestry. In front and away stretched a floor of clouds that were bronze, lilac and emerald, with pools of rose-red fire in them that must have been reflections of the sun."
DS14: "Sirius backed up along the hallway, and stared.
"Through the door came a trio of young women, clad in filmy white, two carrying lanterns shining with a soft pale light, the tallest playing a little harp that echoed a strange, sweet music. As they drew nearer, Sirius recognized them as veela."
DCWH p. 194: "'Is it morning already?' asked the Prince hopefully.
"But it wasn't. Through the door came a troup of maidens, clad in filmy white, some carrying lanterns shining with a soft pale light, others playing little harps and pipes so a peculiar sweet music filled the hall. At once all the skeletons froze in attitudes of fright, and, as for the Oggrings, they lifted in a frenzied cloud and fled out of a high window."
DS14: "Sirius stopped alongside his friend and stared. Instead of a roof, this room was open to the sky, except where it was crossed over by four metal chains joined together in the middle. And from the middle, a fifth chain of brass, each link as large as a cartwheel, dangled down into the room, connected by an S-shaped link to the centerpiece of the room: a huge serpent, as big as a house, made out of overlapping plates of copper and glass. It was coiled around and around a tall marble pole, topped with a carved marble skull with a serpent protruding from its mouth: a sculpted Dark Mark. Sirius could see through the transparent parts of the metal serpent's body to an intricate system of brass cogs and gears inside, turning in regular rhythm. Black steam puffed from its brazen nostrils, and fire flickered behind its huge empty eyes.
"With a determined look, Fleur strode into the middle of the room, walking very quickly."
DCWH p. 274: "'Look up,' said the horse.
"They all did. Instead of a roof, the room was open to the sky, except where it was crossed over by four metal chains joined together in the middle. And from the middle a fifth chain of brass, each link as large as a cartwheel, started up into the night towards the spot where the clock moon hovered."
DCWH p. 200: "The second thing was that the crack split wide open so that the tower separated into two halves, and out of the middle a glittering, huge, terrible thing uncoiled itself, its metal cogs grinding together, black steam puffing from its brazen nostrils, and fire flickering behind its empty hungry eyes.
"It was unmistakably the Dragon of Brass."[end of chapter 3, "Ysome"]
(Note the matching reversed modifiers in the paired phrases "metal serpent"/"brass cogs" (CC) and "metal cogs"/"Dragon of Brass" (TL). Also, for TL's brass dragon to uncoil itself, logically it must have been coiled around the center of its housing structure to begin with.)
DS14 (the metal serpent's defeat): "Sirius might even have said that it was wearing a surprised expression. Suddenly, its head drooped, and there was a thud inside it, as if something had exploded. A good deal of white smoke poured out of its joints, and bright flashes went off behind its eyes. With a tearing noise, it collapsed in on itself, scattering bits of glass and copper across the floor like bright confetti."
DHWC p. 203 (the brass dragon's defeat): "First it hesitated and looked surprised. Then it shook itself, jumped into the air, and kicked out its six legs, one after the other, and looked even more surprised. Then there was a thud inside it, as if something had exploded, a lot of white smoke came out of its joints, and bright flashes went on and off behind its eyes. It ran on the spot, ran backwards, tried to run backwards up the wall, fell down again, and finally stopped quite still."
DS14 (Ginny et al. viewing their army): "They were a mass of huddled figures in the darkness, punctuated by bursts of wandlight. A discontented buzzing rose from them, as if from a hive of wasps.
"'They don't seem happy,' Draco observed wryly."
DCWH p. 289: (the Prince and his horse viewing their army): "Despite what Vultikan had said, and also the fact that they seemed to be dressed up for some sort of battle, they didn't appear to know why they'd come. They stood around, and a droning, mournful noise rose up from them like a cloud of wasps.
"'What shall I do with them?' muttered the Prince."
DS14: "She looked where he indicated. Inked on the floor in what looked disturbingly like - but certainly couldn't actually be - blood, was a circle inside of which was a sketched five-pointed star. In between the points of the star were drawn various symbols: a dot, a cross, a square, an oblong, and something that looked a bit like the letter 'H.'
"'It's a Draxagram,' said Hermione, looking a bit unhappy. 'It's Circle Magic - this one's got a pentagram in it, so it's got something to do with summoning dark forces. Wizards use them for summoning magical creatures, especially powerful ones that you don't want to get out of control. They can't get out of the circle when they appear.'"
DCWH, p. 182: "'What's a Bezzlegram?'
"'It's a circle with a seven-pointed star in it and drawings of safe signs in between the points. It keeps Bezzles out."
"[....]The horse proceeded to draw a Bezzlegram in the dry ground with its hoof. It looked just the way it had said it would, a circle with a seven-pointed star inside. The 'safe signs' were a dot, a cross, a square, an oblong, a thing like the letter T, a thing like an H, and a thing that didn't look like anything at all: [followed in the text by an illustration]"
(The word "Draxagram" first appears on p. 191 for a similar protective ward with a different description, and is used several times thereafter.)
DS14: "Huge tapestries hung along the walls, depicting scenes out of dreams: in one, a castle of bone rose from a bleak wasteland, in another a silver chariot shaped like a flower was driven across the sky by huge fiery-winged horses that reminded Harry of the horses that drew the Beauxbatons carriage."
DCWH p. 184: "The very last thing he saw as his eyes closed was a silver chariot shaped like an open flower, being pulled over the sky by three silver horses with fiery wings."[end of chapter 1, "The Waste"]
(The exact phrasing of "a silver chariot shaped... with fiery wings" is repeated on pp 185 and 243. The castle of bone in the wasteland is a prominent location early in the novella, though I don't think that exact description is used.)
DS14: "Everywhere Oggrings were being dispatched in all their shapes and forms, and unpleasant black flying things glared with horrible fierce eyes, diving and biting at anything that moved. [....] His thoughts were firmly disrupted as he passed a set of double doors; they flew open, and out of them poured twenty or so skeletons dressed in brazen armor and carrying great axes. Skolks. They rattled and clanked across the floor."
DCWH p. 193: "Round and round the Draxagram on the outside beat the black flying things, glaring with unpleasant fierce eyes, and squealing with rage because they couldn't get at them.
"'Are they bats?' asked the Prince.
"'No," said the horse. 'They're Oggrings.'
[....] "Through the open door ran twenty skeletons, dressed in brazen armour and carrying great axes. They rattled and clanked across the floor and surrounded the Draxagram."
(Curiously, CC's version of Oggrings are shape-shifters that are completely different creatures from the "black flying things"; also, the original Skolks are "hideous animals, rather like enormous jackals, with big blazing eyes and evil teeth" (DCWH p. 197) which are not the same as the armored skeletons.)
There may be more; Ginny's dragon, Feroluce, shares its name with a feral vampire prince in Tanith Lee's short story, "Bite Me Not, or Fleur-de-Fur", but DCWH was the most obvious place to start checking textual overlaps. Dunno if I really have the heart to re-read the chapter in parallel with another TL work, though the next most obvious place to check would be "The Castle of Dark", the first half (pp 11-173) of DCWH. The "Lycanthe" is another sideways borrowing which, although the concept and name are credited (at the end of DS6 iirc?), still has certain textual parallels with TL's Lycanthia, but that will probably need its own rather long post.