Ysbaddadan began to grow angry. He enumerated no less than thirteen difficult tasks, together with no less than twenty-six less difficult tasks, all to be accomplished. To each and every one of them Culhwch agreed to perform the deed.
Ysbaddadan wanted the comb and shears that lay between the two ears of Twrch Trwyth, the king of the Otherworld boars, who could not be hunted until the hound Drudwyn was obtained, and the hound could not be held until a leash owned by Cors Hundred Claws was taken. No collar would hold the leash, save that of Camhastyr Hundred Hands and only the chain of Cilydd Hundred Holds could hold both chain and leash.
No one could act as hound-keeper to Drudwyn except Mabon ap Modron, who had been stolen from his home when he was three nights old, and his whereabouts not known. Only Eidoel, his kinsman, had known where he was but Eidoel was in the secret prison of Glini, and no one in the world knew where that was. And even Mabon could not hunt Twrch Trwyth, save on Gwyn Dunmane, the steed of Gweddw, who would have to be fought for him.
Twrch Trwyth could further not be hunted until the dogs of Aned and Aethlem were obtained, for they were never unleashed on a beast they did not kill. To use the hounds, only Cyledyr the Wild Son of Hetwyn the Leper could act as huntsman. Cyledyr was nine times wilder than the wildest beast in the world. Nor could Cyledyr be obtained without the agreement of Gwyn son of Nudd, whom the gods had made guardian of the demons of the otherworld. He could not leave his charge, in case the world was destroyed by the demons.
Further, no leash in the world would hold Aned and Aethelm, the hunting dogs, unless it was made from the beard of Dissull son of Eurei, the bearded giant. Even that would be useless, unless it was plucked from his beard while he was still alive, and then with wooden tweezers. He would certainly not allow anyone to do so unless he was dead.
Neither would Twrch Trwyth be hunted until the services of Bwlch, Cyfwlch and Syfwlch be obtained, together with their three shields, three spears, three swords and their three hunting-horns that sounded so dreadful a note that no one would care if the sky tumbled on them in order to stop the sound.
However Twrch Trwyth could not finally be slain except by the sword of Wrnach Cawr, a mighty giant, and he would never part with it. Lastly, Twrch Trwyth could not be hunted without the backing of Arthur and all his huntsmen.
From The Quest for Olwen, pp384-5, The Mammoth Book of Celtic Myths and Legends, Peter Berresford Ellis from the 14th century White Book of Rhyderch and Red Book of Hergest and also from a thousand year old oral tradition.
Apart from the obvious questions this raises it looks like the final attempt to throw a spanner in the works of a classical quest tale - the hero is set a variety of tasks that he can't accomplish; wanders off either sensibly depressed or naively hopeful to complete them; meets a talking animal, wise beggar or long lost cousin who tells him what to do; he does what he's told; everyone meets their ordained destiny. The difference here is that as well as jamming in props and characters who look like they've been borrowed from other tales, one essential character is in the prison of Glini and no one in the world knows where it is!
Ysbaddadan Pencawr is obviously not keen on having Culhwch as a son-in-law; equally obviously he's heard many stories where people have been set difficult tasks and completed them and drawn the conclusion that the idea was good, but the tasks need to be more difficult.
Sadly the story goes downhill from here. (If you want to know how it ends, here's the BBC's much much shorter version of Culhwch and Olwen. The version in Ellis has a few more twists and turns.)
 If Mabon ap Madron was stolen when three nights old, who told you that he is the only possible hound-keeper to Drudwyn? Eidoel his kinsman? The same Eidoel who is now in a prison that no one knows where it is? How interesting.
 Culhwch meets two helpful relatives during this story.
 Often in mind-numbing detail and sometimes without a final twist.
 It turns out that Eidoel doesn't know where Mabon is. I didn't expect that to happen.