From publisher description: Heroic Co-operative Deck-Building! What slithers in the lightless crevices far underground? These things do, these mockeries of life, these horrors. Fight them as they slip into inhabited territory, fading in and out of sight like smoke and shadows. Feel your very mind assaulted by their presence, even if no blade or magic strikes out at you. Beat them back, or even reason itself might be over-run.