The Hadeshorn sits at the center of the bowl of the Valley of Shale. It is a broad, opaque and strangely still. It's flat surface glimmers with some inner radiance as if something pulses within its depths. So still and flat, that it is like glass and reflects the image of the night sky.
The Hadeshorn is the resting place of the Druids. If a Druid is already dead, one can go to the Hadeshorn and speak with his Shade. This happens many times during the Shannara series, such as in The Scions of Shannara when Par Ohmsford, Walker Boh and Wren Elessedil must speak with the shade of Allanon.
The Hadeshorn's waters are poison to the living.
Inside the Forbidden the Hadeshorn summons the dreaded Warlock Lord, Brona, much to Grianne Ohmsford surprise.