You'll find the full patch notes over at the official website, but what I feel is worth highlighting the most is the various and much-needed buffs to Bretonnia. The Kharibdyss will only be available to owners of the most recent The Queen & The Crone DLC, though if you don't have it there's no need to worry as there are also some rather interesting balance changes coming in with the update.
As you can probably guess from the image alone, the Kharibdyss is a poison-spewing monstrosity that deals a high amount of damage and spreads fear wherever it goes, though it pays for all of that power with a rather slow movement speed and a huge, arrow-baiting character model.
In a bit of a surprise announcement, Creative Assembly has now revealed that the Dark Elves will soon be getting the mighty Kharibdyss as a brand new unit.