actually, without the troops from the garrisons, I would hardly have been able to fend off the infinitely respawning enemies whose army grows with each new appearance. It's probably worth reviewing the map balance in this regard—at least increase the respawn period for the turquoise heroes.
In the 3rd month, I captured Vinland, activated the portal, and am moving further through the underground. I've fully hunted down Mass Light/Dark; generally, only Regen and Berserk are missing for a full set. In the Dragon Utopia, I dropped the Staff of Sar-Issa; I'm currently compensating for the lack of same-turn casting with the druids' channel.
Regen is near the outpost by the first Castle (Mev was sitting there, I think).
As for the turquoise, this was done so that any enemy hero isn't just "one and done" and can put up a fight against the player. That's why I took this method from my previous map, where it handled this job well.