The cloak for necromancy can also be disabled with a single checkbox.
I'm saying that even though I didn't build any gargoyles, I had two hidden spots right next to the castle – one for gargoyles and one for gremlins. Mostly, I was just unlucky and didn't have time to build GM5. Although, on day 115, I took a secondary castle, and on day 121, I already had three castles, while Pete only had one the entire time.