Favorite secondary skill.

I have Diplomacy. It's especially useful on generated maps where there are many powerful units of different levels guarding artifacts. By the third month, with this skill, you can assemble a truly devastating army that will overwhelm any enemy without significant losses. Plus, the artifacts that these monsters guard are usually quite powerful. And if the hero's army has at least one Rogue (or if the spellbook contains Vision, but the first option is, of course, better), you can perfectly calculate how much it will cost, under what conditions the units will join for free, under what conditions they will flee, and under what conditions you will have to pay. Although these large units cost a considerable amount of money... But you can save on the resources spent on level 7 units.