“The key to faking deaths is a fine appreciation of arterial spray patterns. I have found that blood bags work very well at simulating spray with a strategically poked hole; apply pressure to the bottom of the bag, practice a bit, and before long you will be able to write stories of carnage and odes to gore.
A small fan brush-the sort that one dude used to paint happy little trees-can paint a picture of blunt force spatters if you flick the surface properly. You could even talk to yourself, as that painter did, while you flick blood around: "And maybe over here we have a nice stab wound. And, I don't know, maybe there's a few more back over here. Multiple stab wounds. It doesn't matter, whatever you feel like.”