Roah is an unscrupulous trader who has come to the goblin camp with the intention of buying goblin prisoners as slaves and selling Smokepowder. She is disappointed that the goblins are no longer willing to sell their prisoners, since they are now sending them to Moonrise Towers. She is more than willing to trade with the party, if they have coin.
Roah can be found west of the central chamber of the Shattered SanctumX: 275 Y: -29, where she is accompanied by her bodyguards, Erna and Yerle.
Act Two
The Zhentarim trader can be encountered again in the entry hall of Moonrise TowersX: -174 Y: -176. Roah mentions the lucrative smuggling she does for the cult of the Absolute. Rogues receive a special dialogue option to use Thieves' Cant to ask for a discount.
Act Three
If Roah was killed before Act 3, then she can be found making a deal with 'Jaheira' in the Abandoned Cistern portion of the Lower City Sewers after the party has first encounters Minsc and 'Jaheira' in The Counting House. Initially, she is part of the battle that ensues. However, if not immediately killed, she takes the opportunity to flee the sewers.
At the Guildhall, Roah and her Zhentarim have staged a coup, attempting to replace Nine-Fingers Keene as leader of the Guild. If Roah survives this conflict, after the battle, she will move into the former Guild Master's office and resume being a trader with her existing inventory.
If Roah is dead in Act 3, then she will be replaced by Boss Friol.