Diablo 3 has gotten a new patch which brings a major change to co-op gameplay. Previously as more players joined your game, the difficulty of monsters would scale up - this included not only their health but their damage. The patch has removed the damage scaling but left the health scaling in tact. It's a curious change, one that Blizzard hopes encourages players to play co-op more. The patch also makes pots drop less gold than before. I guess calls from the anti-pot destruction league worked.