You can make barricades out of barrels and packages. The ghosts at the start of the first level can get through barricades easily, but just a couple packages can be used to block the summoned ghost in the citadel. Barrels can be tossed at monsters to do damage (breaking them first makes them larger and more effective).
I was disappointed with the number of painted containers in the Sacred demo. I found a large pentagram in a building and automatically tried to light the candles at each point to see if that would do anything, but of course it was just background.
