AI

[Seravy]

Behemoths have 40 caster. Magicians are better with focus magic than javalineers, hell hounds, orc warrior hero, or other units i've seen them cast the spell towards.

Having the spell on Behemots only unlocks Entangle (and Earth Elemental). While it's a good spell, making the Behemoth waste 4 turns on shooting a power 3 ranged attack makes it not worth it. For the same reason Archangels are also not included (there are no cost 41-55 Life combat spells anyway)
While working on this I found there was a bug, the AI preferred non-Caster units as targets instead of the intended Caster units. That explains why Magicians weren't targeted most of the time.

maybe djinn?

It was on the list.

[frutagode]

I saw several times that an Ai sorcerer without white books has several Guardian Spirits (Kali, Blue/Black books, Artificier). How is this possible?

[Nelphine]

Black books raise a lot of dead units in strategic combat, so its very easy for AI to get them from lairs.

[Tlaloc]

Overland spell selection
...
For spirits, the AI wants exactly 1 spirit on each plane, unless every node on the plane is already theirs. If they have one, the weight of spirits is zero.

Yesterday in version 3.1 the AI attacked me with 3 magic spirits and 1 naga. Has the "1 spirit per plane" rule changed? The AI was on a small-ish island.

Out of curiosity, how is AI turn order determined? Is it based on banner color, or on the order from left to right on the Magic screen?

[Seravy]

Overland spell selection
...
For spirits, the AI wants exactly 1 spirit on each plane, unless every node on the plane is already theirs. If they have one, the weight of spirits is zero.

Yesterday in version 3.1 the AI attacked me with 3 magic spirits and 1 naga. Has the "1 spirit per plane" rule changed? The AI was on a small-ish island.

Out of curiosity, how is AI turn order determined? Is it based on banner color, or on the order from left to right on the Magic screen?

Yes, Magic Spirit handling has been completely redone, the AI can now send any number of spirits to any number of nodes simultaneously, though to not waste resources, it aims to have at most 3 of them summoned at a time.

Turn order is from left to right on the magic screen, although there still are plenty of things AI wizards do before/after (mostly after) the core AI turns start/end, like diplomacy.
In the original game, turns were done by task instead of by player - first every AI wizard did overland spells, then they assigned orders to units, then units moved, then diplomacy etc. Which resulted in horrible performance because units moved from the spot the AI saw them at when it assigned what to do. I fixed this for casting and moving units etc, giving the AI players an actual "turn", but everything handled outside of the AI turn procedure still follow the old "everyone does task X now" order.

[Nelphine]

Is it possible for an AI to build too many settlers?

1408, Hard, I do not have Myrran retort - just found the troll wizard, and his capital has a population of.. 3. No contact with other wizards, no meteors or other disasters that have struck him (unless it wouldn't give me the pop up? But there's no corruption or anything around.)

I've found at least 8 of his (well they were his before I defeated his capital) other cities, and I'm assuming there are more..

(Also, I shouldn't have played this game. My level 5 beastmaster hero with an enchant item bow, enchant item plate, and a necklace I found - divine protection/+4 defense - just took on 6 hydras in a lair by himself and won without taking any damage or casting any spells. Heroes are.. insane. But I hadn't proven it to myself for months, so I wanted to see if it still was. I've also defeated two wizards after only taking their capital - they didn't start the spell of return. I believe they had 0 mana.)

[Tlaloc]

What enchantments were on the bow and plate?

[Nelphine]

True sight (plate), Exorcist (Bow); otherwise, maximize attack/defense/to hit/movement/resistance (in that order).

[Seravy]

Is it possible for an AI to build too many settlers?

The AI cannot build a settler if pop<3 so it won't drop it to zero. (Capitals cannot go below 1 anyway)
It's a familiar situation, I often have low population in my capital as well.

just took on 6 hydras in a lair by himself and won

Hydras are bad against heroes (unless buffed). They're effectively a 9 figure unit with only 9 swords, so they don't hit much harder than a high level orc Horde if the hero has high defense. (15 defense with lucky is usually enough to take barely any damage)

[Seravy]

ehhh...found a bug that causes the AI to give random priority to Shatter and Vertigo causing those to be cast instead of good spells like lightning bolt. I bet I would have lost this game already if this worked correctly.