Well it is supposed to function
like the Sacrificial pit. You sacrifice a female Quilboar that is past birthing age and get either a permanently ethereal spellcaster or my "
Stalfos Razor/Skeletal Razormane", that lowers the enemy's damage value and the armor slighty.
You can only make it function like this via trigger. The normal sacrifice ability won't work.
Edit: It is also supposed to be the last tier building.