Though it goes unmentioned on the Asheron's Call Website, the game's December update is now live, adding a new race, playable Olthoi, a new school of magic, a new hunting area, new quests, and more to Turbine's MMORPG. According to this forum post the associated scheduled downtime should be complete, and a list of the new features follows.

Playable Olthoi
Players can jump right into the PvP action as an Olthoi! The evil race of bugs that started it all is now in players hands. Starting out on Olthoi Isle, players can get all the action and excitement of PvP right from the start, playing as an Olthoi Soldier or as one of the winged Spitters.

New Game Mechanic - Luminance
The newest end-game mechanic, Luminance, has been introduced to the game! Players over level 200 can now increase their abilities even more with this new feature. Improve everything from Critical Hit success, to your ability to craft. With Luminance, it is all about choices.

New Race - Empyreans
The fourth new playable race added this year, Empyreans were once the masters of Dereth and beyond. Asheron had sent them to Portal Space to protect them from the Olthoi, but now some have managed to free themselves and have returned to Dereth.

New Magic - Void Magic
Asheron’s Call continues to evolve in all aspects, and the magic system is no different! With the December event we are proud to introduce a new school of magic, known as Void Magic. This is a mastery of a darker form of magic, which focuses on Damage over time.

New Hunting Area
Located in the icy northern part of Dereth, this area for those level 200+ is littered with creatures that most will find familiar and some that are not so familiar.