Balrog Losing Health Bug
The Balrog loses health when using the Breathe Fire ability while there's a fire around him (fire caused by the Rain of Fire spell cast at or near him). I'm not sure if it's fire in general, or just fire from the Rain of Fire spell.
Issue originally reported here: http://www.gamereplays.org/community/index.php?s=&showtopic=633596&view=findpost&p=9821946