According to Zaroff, what is the most dangerous game

Zaroff thinks the most dangerous game is hunting humans simply because they can reason. Zaroff is of course a rather far fetched character. The guy lives in a gothic mansion on a near deserted island and hunts people all day. Still, he does fancy himself as civilized. He certainly follows the protocol of civility but again, the guy hunts people for kicks. I'd have to say that this doesn't qualify him to be civilized.