Fighting Demons

I was in a cave of sorts, with Elves, Dwarves, and Men, all united, to fight a huge battle.  In one corner of the room, two of each race were huddled, readying themselves to summon a demon to kill.  As they started chanting, I realized that none of them actually knew how to kill the demon they were summoning.  I knew that they needed a certain sword to kill it, or it would never die.  This sword was entirely black, and had a large black gem imbedded into the hilt.  I searched amongst the chairs in the room, and finally found it in the middle of the room, towards the side, in the shadows.  The room became darker and darker, until one of the walls were entirely black.  It was from this wall that I knew the demon would appear.  I grabbed the sword, and readied my self to slay him.  When he finally came through, he was a very large troll like character.  He started to swing a club he had in his left hand, but I stabbed him in the chest.  He didn't react at all to the sword in his middle, but it seemed that his club was insubstantial as well.  I kept trying to kill him, but my sword would just move through him like it might through muddy water.  Finally, I made one huge slice through him from left to right, all the way through his middle, and when I got all the way through him, he popped , and his upper half slid onto the floor next to his feet.

We then went through the portal he had come out of, to see what we might find.  We found tons of strange creatures that had been enslaved by the demon, all of whom wanted to come into our realm, and experience freedom for the first time.  Some of them we let through, but others I knew we could not.  They were the ones with only one eye, that I knew would only ever experience ridicule in our world, and would never truely be happy here.  They were very sad, but must have understood, because they did not attempt to walk through with us.  There were a few minor demons left in that realm, and those we threw into a prison we had nearby.