Its almost been 1 year since the Keep of the Witch has released. That said, the story hasn't been fully completed, but with the extra boss it shall. Currently I've completed the Model and the first phase stage of the extra boss so the release may take a while. And, well...
The next update, v1.3 will be adding the thing and some small fixes. It will come out soon and... I hope you enjoy it.
Here's a teaser screenshot of the boss.
-regalfang