Today, Valve introduces Legion Commander into the Workshop, enabling users to design and custom items for her. Fixing some gameplay bugs, they have updated the matchmaking system as well as the User Interface. This comes together with the announcement that there will be a Chinese New Year themed event in late January, along with a standing invitation to artists for submissions for the event.

Dota 2 Update - December 18th, 2013

Added Legion Commander to the workshop.
- Updated workshop files for Dazzle, Dragon Knight, Bloodseeker, Broodmother and Batrider that include separated fbx and smd files.
- 5 solo players will never match against a 5 man party in Ranked Matchmaking (and will be extremely unlikely in Unranked).
- Fixed bug where you could have multiple recruiters, or active recruitment requests once accepting a recruiter.
- Some players with multiple accepted recruiters will have their recruitment status reset.
- The armory filter dropdown will no longer be hidden by any active Battle Point Boosters.
- Fixed various crash bugs around Guides in Frostivus.
- Improved audio mix of player and caster voice on surround sound systems.
- Fixed a crash on systems with multiple gamepads connected.
- Fixed a case where backdoor protection would not function properly.
- Fixed Ember Spirit base HP regen being 0.25 instead of 0.75
- Fixed Naga Siren base HP regen being 0.25 instead of 0.75
- Match history now shows MMR and change for your ranked matches.

Source: Dota 2 Store, Dota 2 Blog