Rock Band 4 December Update features:
- In-game notifications of leaderboard events with an all-new in-song indicator
- Activity feed that enables you to quickly jump to a track to regain your dominance
- Taunt system from the results screen, with the ability to send selectable randomized Taunt messages
- Improved Calibration (require you to recalibrate)
- Variable Breakneck Speed (up to 2.5X )
- Full Combo Recognition & Indicator
- More Song Results details
- Player Stats
- New Items in the Rock Shop
- Auto-kick mode, which will be available as a toggle in the Options menu
- Other bug fixes