From the Mouth of Madness

I know of a draught that should jolt these gibbering former slaves back to reality. Gather some stonebloom from the rocks around Gar'gol's hovel, some bitterblossom from the shores of the nearby lake, and a darkflame ember from one of the braziers at the hovel entrance. The draught won't last long, so combine the ingredients at a twilight cauldron by the entrance to the hovel. One sip of that draught should knock some sense into the brainwashed slaves!