Added 2 minutes later
Limes Inferior doesn't work at all; the AI kills with powerful magic. At 160%, I managed to break through the right garrison by the end of the second month, but the hero's development turned out poorly; I didn't get attack as a secondary skill. I haven't replayed it yet.
Added 2 minutes later
Hiding is risky because two overpowered flags will soon appear, and by that time, it's best to have already moved down to attack the Necromancers. Killing enemy bosses doesn't bring much benefit; they return soon after.