Here's the nightmare I had last night. Gonna start writing these up whenever I have them.
You are in a sprawling 1-floor apartment, trying to hang out with someone and play a board game in an unused room. You notice a set of wooden stairs, going down, in the corner of the room. Looking over the edge, you see that the stairs descend for hundreds of feet, crisscrossing with landings every ten steps or so. There is someone/thing coming up the stairs.
The thing is human-looking but is not human. It moves stiffly and its jaw is fixed open, its eyes white. It is male, wears work clothes and has a short haircut. You run with your friend to a living room where a couple of other people are hanging out - one female, one child. The thing jerkily pursues you, grabbing and lunging. Looking for an axe or something to kill it with, all you can find is a butcher knife. You make do; you chop repeatedly at the thing's neck and open a ragged hole, but no blood comes out, all you see is dark reddish-purple meat. It groans and collapses, but won't stop moving or grasping at everyone. It needs to be completely dismembered.
Everyone helps, and the thing is finally cut into many pieces, but the pieces still won't stop moving. Someone has trimmed off the thing's fingernails, and when you go to collect them, they dig into your hand. The thing needs to be completely destroyed. You gather the pieces and take them in the kitchen, and dump them in the blender. There is no liquid aspect to this thing at all - grinding up its parts yields a crimson sawdust.
The child is helping you with carrying parts into the kitchen and dumping out the blender. Both of you are covered in the dusty remains, and as the child is walking toward you with an armload of limbs, it begins speaking in a man's voice. It says "I cannot be killed by grinding." The child has become infected by the dust; its eyes turn white as particles enter its bloodstream.