HDH in BGB on godmode

Is there Hack that is known to exist to explain a DH that was in combat nearly 100% of a BGB, and received visually confirmed hits from players but his health remained at 100% without changing during any point where I saw him already in combat and personally sent quite a few Sniper Shots and Rapid fires his way? Everyone he reached died in 1 to 2 seconds as well. Players in the match mentioned something was wrong with his stationary healthbar and far higher than even a HDH damage and I agreed it was not like any player I had seen before.