http://maplestory.nexon.net/news/5110/v-168--reboot-update-preview

On December 2, a special server will be open, various classes get balaenced, a Battle Analysis System is added, Zero can be made, and holiday events and such.

The special server, called Reboot, is the big part of the update.

On the Reboot server, the following changes are made for just this server (all other servers are unaffected):
-monsters are stronger and grant more EXP/Meso and drop equips relevant to what class you are
-Item enhancement is simplified
-less dependancy of the Cash Shop (useful items from Cash Shop can be bought with mesos instead)
-can't trade with other players (no economy)

I`ll be checking out the new server along with /msg/, if anyone cares to join us.

Also, here's more info about the Reboot server and the class changes from KMS

http://orangemushroom.net/2015/07/08/kms-ver-1-2-239-maplestory-reboot-reboot-world/

http://orangemushroom.net/2015/06/24/kms-ver-1-2-238-maplestory-reboot-character-balancing/