Amy Lee (the singer of Evanescence) was walking through a mansion. She was mostly chanting things in a demonic voice, but occasionally she sang. I don't remember all of the lyrics, but they seemed to concern, "Treat others the way you want to be treated." Occasionally the scene changed to a dying tree that was covered in barbecue sauce. Eventually, an alligator that I'm going to guess was between 5'5 and 6'0 (perhaps slightly taller) jumped out from inside of a mirror and started chasing her. She ran for what was probably hours in the dream. Eventually they were in a room with a toilet (I wouldn't really call it a bathroom). Amy conquered her fears, obtained a chainsaw out of nowhere and killed the alligator, placing its dead body inside the toilet.
Unfortunately…
That buff orange-haired guy with all the weapons from The Grim Adventures of Billy and Mandy (I think his name was Hoss Delgado or something?) jumped out of the dead alligator's mouth. He cut Amy's head off with his own chainsaw. He then said something I couldn't make out because he had a very strange voice. As he was speaking, most of his teeth flew out of his mouth and the ones that didn't became wrinkled. This scene repeated two or three times.
Somewhere in the dream there was a part where two zombies were screaming and I heard it very loudly because I was wearing a pair of headphones that was plugged into an opening in one of their heads. I don't remember exactly how far into the dream it was, though.