Tenebrae Consumens

At-will, standard action, circle 4, concentration, DC 21+; you create an area of entropic darkness that devours energy. The area is completely dark (as Tenebrae Profundae), and any creature that starts its turn within it or enters it for the first time on its turn must make a Constitution save or take heavy necrotic damage as warmth, light, and vitality are leeched away. On a successful save, they take half damage.

• DC +4: the darkness also suppresses magical effects and abilities within it. Active spells within the area are suppressed (as if in an antimagic field) for as long as they remain inside.
• DC +2: increase the radius by 1 (stackable).
• Fire and light spells cast into the area must overcome your spell DC to function; otherwise they are snuffed out.