Mistborn

I'm in a temple. There's a priest there too. I kill him and steal his knife. The knife is beautiful and there are jewels on it. I get a feeling that it's a magic knife. I use it as a key to open a door. An evil zombie queen lives on the other side of the door. The knife doesn't open the door, but it activates the queen. After that I stand back to see what happens. Some army people appear (A man and a woman I think). Zombies start coming through the door. The army guys start shooting at the zombies, but there comes more and more zombies and they aren't able to kill them all. I start helping them by throwing things at the zombies. When that's not enough I pick up a body (I'm not sure if it belongs to a zombie or a human) and throw it at the zombies. All the zombies it hits die instantly so I pick it up again and touch other zombies with it until they're all dead.