I played the Peninsula map against the AI. Heroic. I was Dungeon, AI was Academy. All in all I was satisfied with my play and with hero development; I did get to Dragons and I won an early clash in the underground when both had skeletal forces (opponent ran after battling a bit). Some time after that he came back - with a vengeance. The AI seems to see your heroes: as sson as I would hit the boat with my main hero, the AI's main hero came; when I would leave the boat the next turn, the hero would go back.
The Thieves' guild showed that his hero had better stats - mine were not bad, though: I was 5 points behind all in all, most of them in the Knowledge department, I had expert Luck and so on, I had the Elemental Waistband and a killer Meteoer Shower, empowered. I had lots of Knowledge as well, 7, and enough spellpower, so I refrained from any manoeuvering: splitting off a halfway decent force to go off to the middle island while keeping enough to keep the AI at bay MIGHT have been possible, but I wanted to see, how a fight would be.
So I lured the hero to me by staying in the boat. He did kill my support hero, but didn't want to attack my main hero (which is a point that needs correction: the hero should have attacked him). So I attacked the next turn. I pretty much had everything with me, level 1-4 upgraded, level 5-7 not. The AI only had upgrades. There were no Golems, though; I had killed a lot in thet first encounter (the force had consisted of mainly Golems and a few Genies (!)). AI had 11 Titans, 18 Rakshasas, about 36 Genies, 50 Archmages, 100 or so Gargoyles and 160 Master Gremlins. I haf 7 Shadow Dragons, a dozen Shadow Witches, 30 Hydras, 40 Raiders, more than 50 Minotaurs, 60 Furies and a little over 100 Assassins.
You know, the armies are completely okay. The AI doesn't get any extras but can build like on easy mode - which is exactly what I expect when playing Heroic.
You know what killed me in the end? The Wizard had expert Sorcery - made all the difference. He obviously had expert Light and at least Advanced Summoning because he did cast Resurrection and Summoning Elementals. For a time the fight looked tight, even though his hero had a lot of turns. But then the AI hero "developed" the killer tactics. He resurrected his rather decimated Genies up to 29 again with two castings and then cast Phantom Image on them; killing an Image against a hero with that high a level isn't that easy (you'll get missed messages frequently). When it was the hero's turn again he cast ANOTHER Phantom Image on the Genies (or on the Image) and that was that - game over soon after that.
So it looks like the AI develops their heroes well - expert Sorcery, expert Light Magic and advanced Summoning plus assorted spells doesn't look that bad and the battle strategy wasn't bad either.
Anf it taught me a lesson: Get Sorcery for every hero you want to cast with - which are pretty much all of them.
All in all a very enjoyable game which tells me, I'm going to have a lot of fun with this game.