Demon invasion.

Maximize the acquisition of upgrade items in the first part, but without dragging it out.

This is unrealistic because they are guarded by 7th-level creatures... In the 2nd month, 2nd week, the library is guarded by 100+ Colossus and Titans, and even more. The School of Enlightenment is guarded by hundreds of fire-resistant Priests. If you visit the colored players through the portal, you can find various angels, and now I have 190 of them... Even randomness won't save you here. The Crystal is now guarded by hundreds of Succubi who are immune to Devil's Strike and cannot be extinguished by a wave.
Why is there a fountain near the city? Okay, if you really need to raise mana, you can spend the night there at worst. The fountain is needed not in the center, but near the second bridge, somewhere near the witch's hut. That makes sense.
In short, you need to think.
I'm going to clear out a couple more neutral creatures and just stand here until someone comes to me.
P.S. I think I've accumulated enough resources; I feel like only Crystal Dragons, a bunch of angels, and a bunch of different Titans will remain from the neutral creatures. The last important upgrade is guarded by them – that's bad