Sacrificial Pit – how to use it correctly?

Kill minotaurs? No, that's too much... They send reinforcements from: if there's a refugee camp, from another castle, etc.

The whole point is that there's no one anywhere. No refugee camps, no other towns, no one joins you. That's when...
I don't really want to fight minotaurs either... It needs to be really worthwhile. Approximately on what week, with what buildings/creatures, which hero, and when should you attack.