Which skills are best for a hero?

For neutrals to join: 1) The undead army must be MUCH larger than the neutral one; otherwise, don't even count on them joining. 2) Read the manual to the end and find out which parameters affect the chance of joining, and you'll be happy. With a certain amount of luck and skill, almost every other group of neutrals will join you. I'll tell you a secret: at the beginning of the mission, it's already predetermined who will join you and who won't. So, you just need to know how.

Added 5 minutes later

We need to try to calculate and create some kind of table for joining, for example, based on the weekly increase in undead creatures in our city and neutrals on the map, depending on their numbers: few, several, group, squad, many (I think a larger number will no longer join us)...

Hehe... You can join hordes and hundreds, with a certain level of skill:D