Brandyr is a NPC and one of the overarching BBEG of the campaign that parallels the actual campaign's BBEG.
Not much is known about Brandyr beyond that he is a powerful spellcaster with past ties to several characters.
Brandyr tracked down Gelabrous Finn and won him in an arm wrestling match. He met a young Sir Willimet as Doctor Forescythe and is responsible for the affliction affecting Sir Will's brother as well as the deaths of Sir Will's parents (in dragon form).
Similarly, Brandyr cast Feeble Mind on Gelabrous in Episode 70, leaving him in an enfeebled, vegetative state and removing him from the party indefinitely.
Brandyr posed as Amir while the party sought to re-light Minderhal's Forge and revealed himself to them after their defeat of Urathosh. As he swore to do after enfeebling Gelabrous, he swung the Hammer of Uskroth on Minderhal's anvil. He then restored Umlo to life claiming it to be a gift of knowledge to the party, transformed into a dragon and escaped with the body of Della Narn.