Global Agenda Halloween event? First make sure you patch up to the latest client build (version 1.38) which hits the live server today. Scheduled downtime is currently listed as 11:30 am to 5:00 pm Eastern, and the patch will be introducing a fairly large number of changes to Hi-Rez Studios' third person shooter MMO.
Chief among the tweaks are new weapon loot drops, new achievements and associated rewards, a challenge function, and an inventory overhaul that sees most items shared across your account rather than specific to certain characters. The challenge mechanic enables pre-made 4-man teams to /challenge one another, and can be used for everything from impromptu shootouts to player-run tourneys and brackets.
Hi-Rez has made the full patch notes available for your perusal, so head over to the official website and check them out.