Yea, the power curve can be a bit of a bitch at times. Losing an army isn't the end of the world, but if you're not powerful enough to take out militias, you're just fucked.
The further you go the more advanced the enemy gets in comparison to you*. The AI here has a militia that he simply puts in every province he takes from me that consists of 11 enemy troops that all outlevel mine and outperform mine. I simply can't take them out without losing the army and thus losing the province the next turn due to the enemy invading again.
*This means that letting turns go by for energy on the astral part only makes the AI that much more stronger.
That's good to know re:passing time on the astral. I've only played the first campaign map so far (albeit three times, heh). And that exact point is what happened in my early game: I couldn't break their militias.
Outposts with a single militiaman in the garrison are a fantastic way of stalling your opponent. Surround their stronghold with'em and you're able to easily clean out the rest of their towns. Not exactly cheap, but damn effective.
You don't even have to build outposts. Take the provinces, have a hero nearby for security and ploink down the cheapest garrison (usually the militia one) in the province. As soon as the AI attacks a province use the hero to invade it back again. Meanwhile use other heroes to gobble up whatever other territory he has untill you can start the siege.
You don't *have* to, but they give you another few turns to clean up nearby provinces before dealing with the enemy hero. Without surrounding the enemy with outposts, you'd quickly burn just as much gold replacing the various militias that you're having to replace every couple of turns and you'd be forced to intervene immediately with your hero. With outposts, the enemy hero can sit there uselessly for a few turns before my scout/commander returns to steamroll'em.
In my game, I had 3 heroes, with the archer being comically overpowered and running around doing most of the heavy fighting and then a warrior and commander doing a lot of exploring and clearing out the less tough dungeons, in time becoming quite strong themselves. My archer was level 27 at the end, my warrior 15 and commander 6, the commander seeming the most useless by far. It's all very well that he gives major bonuses to his troops, but those aren't going to do much good if he can't contribute to fights at all when he's low level, meaning I had a much harder time leveling him than my other heroes.
Archer's are comically overpowered in one sense only: Single target damage. They're *great* against something like a dragon or any small group of high tier units (Provided they can use double shot, ie they can keep the enemy at range). Against a large group of mid/low tier units, though, and they quickly run into problems. You're also hamstrung by the fact that you give up most of your damage potential when using support spells like slow that are vital to the success against many mid tier units. I've also had a lot of success with the commander, actually, as he'll gain enough command to clear out lairs with units alone. Throw in the troop bonuses on top of that, and you're looking at a great second hero choice. His lack of combat effectiveness actually helps his case to some extent, actually, as he's able to just sit back and spam spells like web and slow.
Can anyone tell me how I can get to build more buildings in my provinces? After I build a few, it says I have run out of space. What is the cap on buildings per province and is there any way I can raise it?
Some building types have a max restriction. Troop buildings, for instance, have a limit of four and it's impossible to destroy them and switch troop types. I actually fucked up my first game because of that very thing: I had built all of the "low" end T1 units and couldn't get the firepower necessary to start making progress. These days, I tend to go for a basic setup that transitions well to the mid game but doesn't leave me completely gimped/relying on mercs for the early game: Militiamen, Healer, Pike/Sword, Crossbow. You're also limited in this way when it comes to item and spell buildings.
I still feel like there's tons and tons of stuff I haven't done. I couldn't, for instance, find any way to turn "evil" or "good" or any indicator of how close to evility or goodyness I was. Is it simply a matter of choosing the "muahaha, I am eeeevul!" options in the random events and then you'll get to build dwellings giving you demons and shit? I guess I ended up "good" as my level 4 unit I picked was some sort of paladin, but I miss some sort of transparency for a lot of things in the game.
Part of the charm of the game, at least while I'm still learning the game, is the very fact that the alignment calculations are hidden. There also seems to be a refreshing limit to the number of "muahaha, I am eeeevul!" options. Or, rather, there's actually an interesting dynamic between the various options.