Blizzard has extended the anniversary buff by one day, so make sure you use it before it expires!
Blizzard Tracker: May 21, 2013
Just as a reminder for all players, the Diablo III anniversary buff will expire in the Americas on Thursday, May 23, at 9:00 a.m. Pacific (12:00 p.m. Eastern).
For those of you with characters in our other gameplay regions, the buff will be disable on Wednesday, May 22, at 5:00 p.m. Pacific in Asia and on Thursday, May 23, at 12:00 a.m. Pacific in Europe.
Note: We elected to extend the buff by 1 day, so this time frame is bit later than we first communicated. Apologies for any confusion, but yay for another day of demon-slaying buffs!