Creatures inside, entering, OR viewing the area are entitled to make will saves to resist the illusion. Creatures in the area that failed saves become entagled. While mostly illusory, the hazards you create are partially real. All creatures within the area that did not save take 1d6 points of damage at the start of your turn. All creatures regardless the outcome of the save within 5 ft of each other have concealment, and those 10ft away have total concealment. The caster may make Hide checks in this area even if they are observed (no other creatures gain this benefit). If you use this invocation a second time while a previous nightmares made real is still present, the previous effect ends.