Here's Riot Feithen with more information:
Over the past week the PBE has experienced significant problems ranging from broken AI behavior to crashes to disabled champions, ultimately forcing us to disable most of our game queues. Despite our efforts up to this point, we haven't found a solution that fully restores the health of the environment, so we’ve come to the conclusion that our best option is to restore the PBE to its last "known-good" state from Tuesday, November 26th. The revert will roll back a significant number of changes. As some examples:
We'll be moving forward with this plan tonight. Over the course of the next few days – and into the weekend – you can also expect to see more patches than normal, resulting in more downtime. We’ll get features and content rolled back out safely and update you as things become available.
- Standard queues will be re-enabled
- Snowdown Showdown game mode will remain disabled at first
- Balance changes are being reverted
- Bug fixes are also being reverted
- Particle and model updates (both for skins and abilities) will be rolled back
- New Player Experience content will be missing
- Tooltips and localization could be out of sync
As always, thanks for your patience and continued help testing on the PBE.
Fei"As noted above, the PBE is being rolled back to the 11/26 build - the debut of Snowstorm Sivir.
Here is a list of PBE patches that will be ROLLED back - expect to see this content re-emerge soon: