The essence of the tactics for playing against the Dungeon faction.

Do you mean the Elven faction? And why starting from the second month?

Because, at earlier stages, the Elves don't have enough troops, and the Elves will simply overwhelm them with magic (fast intelligence and artifacts on the desired element guarantee this).

But the end of the second month is only if the Elves are not led by Lethos.

Personally, I don't play against Elves led by Lethos, it's just too unbalanced.