You could trying using Cheat Engine Speedhack for this, though it'd affect the whole game.

If this is too hard, then you could always 'rationalise' that the spell just rebuilds the buildings of the city, and then people of whatever race come to occupy the place that's been rebuilt.

And G, we are here to help you testing. Release the beta, or send it on priv to Southern and me, he will provide you valid feedback :) , and I can [s]have fun[/s] test & report if some elements are not working ( i dont mind reinstalling AoW1 every game). Dont implement anything new.

remove this spell from game.

It's not that sort of testing, it inolves tweaking parts of the code to see whether or not it does what I think it does. My work is 1% actual coding and 99% figuring out what exactly "mov dword ptr [ebx+0000012Ch],00FFFFFFh" does in the current context, or what that context even is.

The reason I messed about with Animate Ruins in the first place was to make up for the Undead's lack of friends, but I'm currently leaning towards restoring the spell to its original behaviour and giving the Undead something else instead, like faster migration (if that's even realistically possible).

By the way, here's what the relation matrix looks like. You can see why the Undead need some sort of compensation.

I don't know if this will help your exploration, but I've been cataloguing current game behaviour here: https://www.gog.com/forum/age_of_wonders_series/aow1_list_of_interesting_design_and_gameplay_bugs

Have you found a way to edit AI behaviour?

Specifically, you can strand indie units and another player can "capture" them, but this causes a table error where the AI refuses to end its turn unless you save and reload the file (AI runs through the table again without error). If this is just a delphi table, is there a way to add a line to end its turn in case of an error?

Do what you like, I hope we don't get on your nerves!
I do have some ideas though -

Assuming the AI never casts that spell, you could leave the bug in and simply warn people not to cast the spell unless Undead are enabled on the map. It'd actually be appropriate that it can't be cast without Undead on the map, just unfortunate that the 'error message' would be a crash. When I'm starting a PBEM I could make sure undead are enabled, this might lead random-race cities being undead inappropriately but that's not a real problem.

On the other hand, Animate Ruins might not be what the Undead need to make up for bad diplomacy anyway. On some maps it might be unavailable for a long time in a game depending on research power, though you could make it cheap and available early, come to think of it. Undead-only or not, the spell would be more useful to the Undead than to other races, because they have more uncooperative races.

You could give all Undead units +1HP, not even joking. In the same way Goblins have 4 HP, it could be lore-justifiable for Undead to have 6 HP. This might sound really unbalanced, but the game copes just fine with having Elephants and Pony Riders that dunk on every other t1 unit, and having Dwarves sitting on mountains and lizards sitting on water completely safe.

Another option is giving Doom Priests (whose image shows them reanimating people) 'Construct' so that they are a cheap way to rebuild cities, but then they could also build other stuff, which would be inappropriate. I personally think the idea of an undead labour force is a cool fantast concept, but in Athla they are a force of pure entropy.

Yet another option is giving the Undead two other diplomatic workarounds. Doom Priests have the seduction of humans in their lore, and have the skill 'Dominate', so maybe they could have Bard's Skills too, so that Undead can use units of other races with them. If you moved the Wraith to Tier 2, then the Undead would also have an easy time occupying/razing cities with them, because of how physical immunity plays vs Raze Defenders. That raises the issue of wraiths then being too strong in general, but that could be limited by giving all priests Magic strike?

Lastly, it's arguable that the Orcs and Goblins could be merely Wary instead of Hostile.

Just throwing some ideas out there.

In the campaign, Dwarves are the most reliable allies of the Keepers (the Elves).

It looks like the racial relations in that image follow the lore of Athla as we see it in the campaign very closely. I just took a look through the campaign text file to check, and am impressed by how accurate it seems. I don't think there is any mention of special animosity or conflict between Orcs and Humans, therefore they are Neutral. Instead the Orcs and Azracs are at odds, and so on.

I do wonder why the Orcs are on such bad terms with the Dwarves, and why the Elves and Azracs are Wary to each other, but I think the campaign text is about to remind me.

The only thing I might propose is that the Azracs and Frostlings might get along Neutrally, instead of Warily, precisely because they are never interested in the same territory? How much do they cool or increase the temperature by their presence?

Relations represent sort of a compromise between lore, alignment, and gameplay. For a while I was even considering an asymmetric matrix where e.g. Elven units/cities are more amicable towards High Men leaders than High Men units/cities are towards Elven leaders, but ultimately I abandoned this idea for gameplay reasons. I did something similar for certain non-race unit alignments, however. I will review some race relations after the patch is released and there is a consensus on balance and where it needs tweaking.

One thing to keep in mind is that the patch exclusively modifies engine files, so anything that would require editing the mapset is out of the question. Of course this means that anyone with knowledge of the developer editor can build their own ruleset on top of the patch.

One advantage the Undead have is that their units don't care about terrain, and the other races have been given more hostile terrains while terrain effect on morale has been drastically increased. On maps with diverse terrain, a single-race terrain-independent army will have a real logistical advantage, and the Reaper might finally be worth something since most other races really hate wasteland.

Regarding AI, I think I was able to change some things but the reality is that AI behaviour is complex, random, and hidden, so without any debugging tools it's very tedious and frustrating to figure out whether a change actually has the intended effect. Solving bugs related to AI behaviour is very very very very low on my priority list; I'm just happy that the AI now occasionally garrisons neutral cities.

It'd be cool to give a stat bonus for very high morale, like the penalty for low morale. But of course ideas are easy, figuring out whether they can be implemented via trial and error with a hex editor is hard.

Can you give 0 MPs left to troops/heroes that retreat from a battle? (To avoid the 2 archers killing dragons thing)

No.

Morale stat boosts would be easy but I'm not sure they're a good idea.

Having Fire Mastery active causes flames to periodically appear and fade away across the map.
In my opinion, it would be nice if the number of those fires was increased, because there aren't many of them, and the other Mastery spells have stronger unique effects.

Also, making Fire less weak in general is beyond what can be done with a ruleset, which can only make spells easier to research and cheaper to cast. Currently Fire is vastly worse than Water. It would be nice to see damage increases for spells like Fireball, Sacrificial Flame, and so on.

One aspect of Fire's weakness is enchantments - Fire Halo only gives Fire Immunity and Fire Strike. It does not give Ignition. The UI text in the spellbook says it does, but the mouseover when it's on a unit doesn't, suggesting that the developers were indecisive about this. IMO, ignition should be restored to Fire Halo.

Then there's Fury. Because archers are so dominant, -1 DEF for +2 ATK is not great. Maybe it should give Cause Fear as well, or +1 DAM?

The ''burning'' effect is pretty weak compared to being stunned by lightning, frozen by cold, poisoned, etc. So increasing the attack and maybe damage of Burning would be nice.

Also, morale stat boosts - maybe like you say it's not a good idea to give a significant boost, but +1 RES would be cool without actually having a significant impact.

Out of curiosity, what sort of storyline would you be thinking for the campaign you mentioned?

The story is sort of similiar to what happens in the centuries leading up to the AoW1 campaign, but set in a different garden. It's still rather vague, though. I'll start properly working on it once the patch is complete.

Magic balance changes are possible but not something I'm looking at before the initial release.

By the way, AoWEd has just received a minor update to enable some previously hidden (though largely useless) features.

What features might those be? Opened it up and had a look, don't see anything obvious.