The Mountain of Despair is a scary and dangerous place that has been seen in every movie, shame, and villain HQ that has ever existed. The Mountain of Despair takes many forms and can be found in many places, but it is ultimately composed of one evil spirit that curses those who dare tread upon it.
The Mountain of Despair is often sought out (especially by villains) because it is a powerful source of dark magic. The Mountain of Despair can be used to cast various evil spells and curses. It also makes a great headquarters or secret laboratory. The Mountain of Despair has become a commonplace asset to villains everywhere. The heroes like this because prolonged exposure to the Mountain of Despair can cause bad luck, insanity, and radiation poisoning.
Nobody knows exactly where the soul of the mountain rests. There are many different "branches" of the mountain that can be found throughout the UnWorld. These branches can take many forms, whether they be tiny hills, huge cliffs, or even volcanoes. The Mountain of Despair is often surrounded by the River of Death. It is rumored that Mount Everest is one of these branches, but it turns out Mount Everest is just a jerk, not evil. K2 probably is, though.