I just read that you will be having "Regular" Darkness and "Permanent" Darkness. I like this plan for covering situations where the darkness absolutely cannot be overcome. However, in games like Pathfinder, there is something called Greater Darkvision which allows creatures to see through Regular Darkness and Greater Darkness (Utter Darkness in RoleMaster). SUGGESTION Darkness Levels: 0-5 0 = No Darkness (0 Opacity) 1 = Twilight (25% Opacity) 2 = Shadows (50% Opacity) 3 = Nornal Darkness (75% Opacity) 4 = Utter Darkness (100% Opacity) 5 = Permanent Darkness (100% Opacity and cannot be bypassed) Dark Vision Levels: 0-5 0 = No Dark Vision (normal humans) 1 = Low-Light Vision (-25% Opacity) 2 = Dark Vision (-50% Opacity) 3 = Greater Darkvision (-75% to Opacity) 4 = Uber Darkvision (-100% Opacity, but won't modify Darkness Level 5) 5 = GM Vision (-100% Opacity, including Darkness Level 5)