This reminds of a memorable game session we once had:Oh I didn't explain the light source thing. It seems the brighter and more light we had(which people want so they can see maps, books, and such) the more intrusive or a distraction it was. The dimmer light it seemed to work.
The party had been tricked into walking into an ambush set by grimlocks in a warehouse. After entering, the door slid shut and their leader cast darkness on them. Before we got farther then rolling for initiative we had a black-out at the place we were playing, leaving us sitting in the dark
