Massacre
The massacre experience bonus in Diablo III is bonus awarded to characters who kill a large number of monsters without any significant pauses between the infliction of damage. Massacre bonuses award some experience, but as it's usually much less than the monsters themselves were worth, the main motivation for most players is the fun factor.
Scores of ten or twelve are easy to achieve in the early going, but much higher tallies of dozens or even hundreds of kills can be achieved in especially-crowded areas, or by players who "herd" monsters or work to entice monster summoners to create a large number of enemies.
Massacre bonuses are similar to and may be comprised of Mighty Blow bonuses, which count how many monsters were killed by a single attack.
Development
The massacre feature was first shown at the BlizzCon 2008 gameplay demo, where most players were enthusiastic about the new feature.
In September 2009, Jay Wilson said in a press conference[1] that the idea came from when the team tried to give the Experience Shrine and Monster Shrine from Diablo II a new twist, making it more like a game mechanic than the only two shrines people cared about.
As of the Diablo 3 Beta test there are no Achievements tied to massacre bonuses, though it's widely assumed there will be Achievements for massacres in the final game.
Media
A Demon Hunter racks up a 124 massacre during the Jar of Souls quest event.
Aftermath of a Jar of Souls massacre.
Photo of a monitor showing a Massacre from the Blizzcon 2009 demo.
