As you can tell from the first 2 scans, the foil cover makes accurate reproduction difficult - the colors are brighter on the actual book.

Although the credits page has an ISBN for "revised edition" - I saw one source who noted the text is copyright 1965, and only the Pronunciation Guide is revised as of 1999.

The Black Cauldron - second book in Lloyd Alexander's "Chronicles of Prydain."

[The flap-copy:]
In the imaginary land of Prydain, where "evil is never distant," Prince Gwydion faced dangers more threatening than had ever been dreamed of. It had become imperative that the Black Cauldron, chief implement of the evil powers of Arawn, lord of the Land of Death, be destroyed. For each of the warriors cholsen to journey to Arawn's domain, the quest had special meaning. To Ellidyr, youngest son of an impoverished king, it meant a chance to satisfy his bitter longing for fame. For Adaon, beloved for his gentleness and bravery, the quest was an omen whose significance he dreaded to discover. And to Taran, Assistant Pig-Keeper, the adventure seemed a gloriou opportunity to wear the his first sword, a man among men. How each fulfilled his destiny in ways entirely unforseen is related in a story filled with adventure and the sacrifices that great achievements entail.