Here is a quick summary of what is updated in October 2016.
This is quite a big update that changes a lot in the game. The game and clan war balance is calibrated, new levels are added, as well as some other changes.
There are new levels for Wizard, Hidden Tesla, Baby Dragon and Mortar. There is a new defense Bomb Tower. Clan war is balanced and you can earn a partial bonus even if the attack fails.
All of the updates are collected and fully documented here on reddit.