Drow Piwafwi Cloak

Drow Piwafwi Cloak offers the wearer a -6 bonus vs. Breath saving throws and +75% bonus for Hide in Shadows and Move Silently. However, this needed is to make progress in chapter 5 of Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition. The cloak needs to be given to Phaere as proof of Solaufein's demise by your hands, which means the cloak can only be used for a short period. Even then, the cloak would turn into Adamantine Dust just like any other drow item.

In-game description
"The cloak can be made in every possible shape with just about every type of fabric. The most common forms are a circular piece of fabric with a hole in the center for the head, and fabric draped from neck, connected by a chain, brooch, cord, or pins. Talented drow weavers have woven strands of adamantine into the cloak, thus rendering it useless if exposed to the light -- the effect of which will turn the cloak to dust."