Razorback Update on the emnity system (BG):

"In order to reduce the enmity gain from dealing damage at higher levels, in the March 2013 Version Update the "standard DMG" values will be increased as part of the revision to the enmity system.
The proposed change will affect monsters level 51 and above, and will result in approximately a 70% reduction in Enmity gained from damage against monsters level 99 and above."