You scream and start running. Really, in a situation like this, blind panic is as likely to help you as anything. Of course, you don't outrun the house-sized hellcat, but did you expect you? It's the thought that counts and you put forth a great (if perfectly futile) effort. The hellcat comes down from the roof of your home, takes a single sprawling step forward, and bites you cleanly in half as you're darting off.