The area becomes a wall of blinding light up to 20 feet high until the end of your next turn. Creatures who enter or begin their turn in a space in the wall immediately take radiant damage equal to your melee damage bonus, and one radiant arcane affliction. The wall grants total concealment - creatures cannot see through the wall but may move through it, and may attempt to attack through it with a -5 total concealment penalty. The wall may not be attacked.
You may expend an immediate action during your turn to sustain the spell until the end of your next turn.