Ander

Ander is an NPC first encountered in Episode 28.
Ander has kept most things about himself secret. He claims to be a part of the Runehunters Guild and was an archaeologist looking into the ruins where Deathcrawl and Aisling had set up shop. He was captured and locked in a cell but the party later stumbled across him and set him free. 
Ander told us how the Runehunters Guild uncovered a large horn buried somewhere far to the north of our current location in the underdark. The Cult of the Dragon seemed to be interested in uncovering it but Ander claimed he did not have the chance to study it and knew very little about the horn itself.
Not much is known about the man but he seems to be some variety of human mage and agreed to travel with the party until they reach Nexus Upsilon. Upon arriving there, he split from the party. When asked about Ander, Tnebrous claimed not to know anyone by the name of Ander, despite the fact that he was in a cell near Tristram, who had been "captured" on Tenebrous' orders.