The Horn of Bran
Marginalia from the Thirteen Treasures of Britain

The Horn of Bran the Niggard was one of the Thirteen Royal Treasures of the Island of Britain. And Myrddin came there to ask for those treaures of everyone who had them; and everyone agreed that if he should obtain the Horn of Bran the Niggard he shold obtain theirs from them, supposing that he would never get the Horn. And nevertheless Myrddin obtain teh Horn, and afterthat he obtained them all, and went with them to the Glass House, and they remain there for ever.

Hercules obtained the Horn of Bran the Niggard from the head of the centaur after he was slain. And then the wife of the centaur wetted Hercules' shirt in the blood of hte centaur, and when Hercules had put on the shirt it was not possible ever to take it from off him until the shirt had eaten his flesh and skin to the bone, and Hercules was slain.

SOURCE: Marginalia in Pen. 147 (ca. 1566). Translated in Trioedd Ynys Prydein by Rachel Bromwich. Cardiff: UWP, 1961.

Also compare with this segment of a poem by Guto'r Glyn:

Brān Galed brin y gelwynt
Bonedd Gwŷr y Gogledd gynt
Taliesin, ddewin ddiwael
A'i troes yn well no'r Tri Hael

Niggardly Bran they used to call him
Of old was descended from the Nobility of the North
Taliesin, no mean magician
Transformed him into one better than the Tri Hael.

SOURCE: Guto'r Glyn. Gwaith Guto'r Glyn. ed. by Ifor Williams & Llywelyn Williams. Cardiff, 1939. p.218, ll.61-4

The Tri Hael are from triad 2:

Three Generous Men of the Island of Britain:
Nudd the Generous, son of Senyllt
Mordafthe Generous, son of Serwan,
Rhydderch the Generous, son of Tudwal Tudglyd
(And Arthur was more generous than the three)