According to Blizzard, ”When we originally designed and implemented the bonus values for monster damage in Inferno, we were unaware that a bug was causing monster abilities (i.e. Rare and Champion affixes) to not scale correctly with each Monster Power level.
“While this bug was caught during testing and did not make it into the game, the result of it being fixed meant that monster damage – specifically damage done by monster abilities – was ultimately higher at MP1 through MP10 than we intended it to be when 1.0.5 released.”
To give an example of how bad it had gotten, Monster Power 1 dealt 114% damage instead of 109.6% - but that ramped up to a ridiculous 371% damage instead of the intended 250.09% damange on Monster Power 10.
The hotfix is due to be available later today.
