The Witch's Mirror - NWN Side Quest (Chapter 2)
The Witch's Mirror is an optional side quest that begins by speaking with Setara in Setara's Home. You can find Setara's Home in the Neverwinter Wood - Heart of the Forest map, it's inside of a cave in the eastern portion of this map. Setara is involved in The Missing Druids, Five Tomes of Imaskar and The Serpent's Gems quests as well as this one. In order to complete The Missing Druids and The Serpent's Gems you'll have to either finish this side quest or kill Setara for the Gem and Key you need.
For this quest you're tasked with retrieving the Mirror of Vanity which can be found inside of the Nymph's House in the Deep Woods map and returning it to Setara. You'll find the Nymph's House in the northeastern portion of Neverwinter Woods - Deep Woods. It's the map just before Neverwinter Woods - Heart of the Forest where Setara's House can be found.
During the main story quest you'll have to visit the Nymph's House anyway since we need the Ceremonial Dagger which can be found inside of the same chest as this Mirror (pictured below). All you need to do is loot the Mirror then return it to Setara to complete this quest.
Your reward for finishing this quest will be Setara's Gem which is part of The Serpent's Gems side quest and Setara's Key which you can use to free Bree who is part of The Missing Druids side quest. Keep in mind that once you complete this quest you can also kill Setara without any penalty for more EXP and loot.