Darkvision is usually a good idea when going into a dungeon.  Technically you can just light torches or cast light spells, but that will tip off the intelligent undead to the fact that you're coming in without them having to make a saving throw.  (though they won't be able to really attack you unless they actually succeed their saving throw)<br/><br/>Aside from being dark, the dungeon is creepy but not otherwise hostile.  The hallow spell is probably what's causing all of the undead to keep slamming into walls and dragging their weapons against the floor.  Don't count on any part of the facility to have light sources; undead aren't inclined to use any sort of light at all, and they all have darkvision.  (Many types of evil subterranian creatures such as Drow do light their environments, out of desire for color and appreciation of light.)<br/><br/>One handy side effect of the undead sitting around in a completely lightless tomb is that you'll be completely invisible to most of them if you get 60 feet away.  Given the size of the dungeon though, that's not particularly practical.