Demon attack.

As far as I can tell, the difference from the original map is that the demon-worshipping faction of the "red" Haven became significantly stronger than the dark elf faction from the previous version, and it's impossible to defeat them with the Stronghold. There aren't enough resources to build a structure with summons (specifically, the life-saving "frightening roar"). And even if it is built, it's not certain that it will be used. However, you can try to make the green hero follow a secondary hero (if the AI falls for it) – this will give you an extra 3-4 days of peace to develop the city, but there are so few resources that it will likely result in a standstill.