I've noticed skinks and bastiladons do extra damage to things with the Chaos Daemon tag, but looking around I'm not seeing many things that have that tag. Is it things that say exactly 'Chaos Daemon' in the keyword, or is it 'Chaos' and/or 'Daemon'?
It had to have both Chaos and Daemon keyword for the ability to activate. For example a veminlord would have both keywords and this boosted attack would be effective against it.