AI behavior towards nodes

[Beorn]

Playing mostly on Fair difficulty, I like that the AI now behaves appropriately aggressively towards unguarded and lightly guarded nodes held by me.  But for some reason, I see cases where they conquer a node from the original guardians, and then much, much later (30 turns?) they still have not gotten a spirit to meld with that node.

Is it possible that they have trouble moving a spirit there, when they have a stack of 9 units already on that tile?  Just a thought.  In any case, it is disastrous for them.  Not only are melded nodes crucial, but they have probably their best stack of units tied up and doing nothing.

[Seravy]

It's probably a distance issue. The AI is limited to use a city in a range of 18 tiles to summon and send the spirit. If that's not the case, it might be a bug.
Of course the spirit can't enter if there are 9 units but it should at least reach the adjacent tile and as soon as the AI has enough units on the continent, some of the node defenders should leave to join other units and build a new 9 stack.

[massone]

On Lunatic difficulty, I see the AI defeat nodes then leave because its stack is too powerful to be used as a garrison. Then it gets garrisoned by some other random Wizard, each taking turns moving units onto it then leaving, and none of them take them for a while, until somebody is both in range and has the right units. This seems to be more effective than it used to be in COM1, as now the AI competes to rush lairs/nodes the same way players do, and moving on without wasting troops garrisoning nodes that won't contribute much compared to capturing more lair rewards faster.

But I am concerned that their efficiency in taking nodes is not working as it should be. I first noticed it in Alpha testing but I never played to the late game so I couldn't put it in context, but it appears to me that Arcanus wizards have become TOO good at taking lairs. After opening the Tower just before turn 140 because all lairs had been cleared by the AI (I barely got 6 lairs myself in the whole game up to that point), I found the Myrrans actually only on par with the top Arcanus Wizards. Instead of Myrrans invading, the Arcanus wizards invaded in force and I had to scramble to compete to take some territory myself instead of focusing on defense as was my plan. The Myrran wizards couldn't capture the hardest nodes on Myrror for some reason, even though they didn't seem any harder than the Arcanus ones with Very Rare creatures (as I went to clear them). The same thing happened with the Towers, as soon as I opened the first Tower, all the Arcanus Wizards rushed the Towers within a few turns, and the Myrrans got almost nothing.

EDIT: Just adding some context, the above happened in a Lunatic Normal sized Large Continent, 1.0 Magic Power, Wet, Rich, map with 13 Wizards.

[Seravy]

There actually is a drastic difference between possible monster budgets on Arcanus and Myrror nodes due to aura size.

Myrran nodes are 8-20 tiles while Arcanus nodes are 5-12.
Monster strength increases with tile count in a non-linear way as far as I remember.
So while both can have very rare creatures, the best Arcanus node might have one of them and the best Myrran one might have four or something like that.
As the AI usually has to beat these in one go instead of multiple fights killing one each, that makes Myrran nodes 4 times harder for them.