US servers will come down on March 5th, 2014 at 7:00 AM Pacific Time for a hotfix. The expected downtime is approximately one hour. EU servers will come down beginning at 9:00 PM PT (6:00 AM CET March 6th, 2014) for the same update. Downtime is anticipated to be approximately 2 hours.

Here are the patch notes:

GENERAL
Fixed an issue where gaining AA experience could display an invalid message.

Temple of Veeshan: Guardian's Edifice
Spirit of Malice adds in the Zlandicar encounter should no longer hit players once for each player they hit with their "Bone Slice" spell.