Negative numbers have been in Redemption probably since it was ruled that characters who decreased below zero toughness in battle didn't die immediately. So a 5/5 Claudia banded to a 10/10 Gabriel results in a -1/-1 Claudia and a 4/4 Gabriel when Hunger is played, for a net result of 3/3. So yes, if you decrease your Sadducees to below 0/0, they can be negative.
