Here is my submission for the MAMA contest. I have always been very afraid of sweet docile things becoming evil and twisted. Also, I have always found basements to be very eerie, they still creep me out.
This is absolutely nightmarish. Everything about this image is intended to scare someone, and for my part, I think it succeeds.
I'll start with the little things and work my way up. First, the eerie glow from beneath the floorboards that illuminates the monster, yet not the dark doorway behind it. Then, the fact that the face of the portrait in the upper left is a skull. Finally the abomination itself; some kind of horse-headed, long-clawed, zombified monstrosity with zombie baby faces growing out of its back. This is not an image that anyone should see unless in broad daylight. Well done.