To do this, add Blood Essence to the Castle Heart by interacting with it.
This will power the Sawmill and all other automated buildings you’ve placed down in your castle.
Without Blood Essence, you’re able to’t use these buildings, and yourCastle Heart will decay.

Then return to it and pick up everything in the “Output” grid together.
The first panel simply indicates whether or not the Sawmill is powered by a Castle Heart.

