Easy solution! Make all the Skink units require hammers, not spawning.
I think this would fix ~65% of the problem immediately, and the rest could probably be balanced.
It would give the player (and AI) something to spend hammers on, it would restore stratregic construction decisions, it would fix the early game, and it would emphasize the weak swarmy core vs tougher rarer dinosaurs of the army.
I think we could bring this up to 75% if you still had to build not just the tier1 skinks, but also could build a few core tier2 units, like militia spearman/militia archer replacements (and their militia swordsmen ideally, but I'm guessing that you wanting your militia swordsmen replacement saurus to spawn as this is your central saurus unit).
Maybe skinks could use the warren ub from ffh2 if they are to be buildable?
I don't think warrens work here.
a) We're already using them for Skaven.
b) they have the opposite effect; if all non-skinks are free, then we already are only using hamemrs to build skinks, so we will have a ton of them. We don't need *another* mechanic to increase the number of skinks.
* * *
Marks of the Old Ones: 6 Unique features that only appear on the map if Lizardmen are in the game (we should be able to code this easily using python, editing the map generation scripts).
If a Lizardman unit is standing on a Unique Feature with an Old One Tablet, they can cast a spell ‘Claim Tablet of the ‘X’’
I massively preferred your old design; each unique feature creates a resource, and then you claim the resource in the normal manner, by having it within your cultural borders, and have the shrine national wonders that each require one of the corresponding resources.
I like this much MUCH better than some kind of ability or spell effect where you manually transport the tablet back to your civ.
And the AI understands how to go about getting resources, and prioritizes building cities in places where it can capture the resources. Giving the features tile yield bonuses will increase this further.
Plus its a harder challenge to have to control the resources and just walk there, but all the features will spawn only in jungle tiles, which form an equatorial belt on mapscripts, so it won't be that infeasible.
Another advantage of this; you could give some units (Slann?) affinity with these resources. So maybe Slann are strength 3 (they're big fat lizards), but with resource affinity for the 6 resources, so they rise to 9 if you control all 6.
Another advantage: you could have the resources revealed only by the Magic of the Old Ones tech, so non lizard/amazons would never get them.
I have no objection to events that trigger on entering the feature tiles.
The one think I would emphasize is that there must be some buildings or events available to the Amazons from the features; the amazons should be the lizard enemies, contesting them for control of the these features.
I would also give lizards (and/or amazons?) Elohim-style knowledge of the feature locations.
Monument of the Sun, etc.
Doing these as resources, you don't need to have the Tablets appear as unit promotions/equipment, so all the affinity you can get rid of. All of the features should have some tile bonuses (either inherent, or from magic of the old ones tech, which both lizards and amazons get).
I would suggest that any extra spell features be a consequence of building the Wonder, not controlling the feature. You could also consider requiring the Slann to be present in the city with the Wonder.
You've also written the spells as effecting *all* enemy units, in the entire world? This is massive, massive overkill, particularly for a spell which could be cast by each slann every 8 turns!
has a 1% chance to turn each grassland to plain and each plain to desert outside of the lizardman cultural borders (this last effect might be too much).
Hmmm.... yes, too much. You shouldn't be terraforming outside your own borders, and honestly I would prefer this mod to have less terrain terraforming than in FFH. The middle of the Empire suddnely turns to desert because some lizards on the otherside of the world start casting searing light? Thats not fun. And why are lizards *destroying* the world (turning it to desert)?
I'd also suggest you consider converting these super-spells to rituals (buildable in the cities - another thing to spend hammers on) rather than spells on the Slann.
Possibly Slann could create an Inspiriation-type building in cities (lasts as long as they are present) that boosts the production of Rituals.
The Ritual method of spawning sounds interesting, better than the planar-gate style. I will think about it some more.
My biggest worry is that the AI wouldn't understand that building those rituals gave it units.
A hybrid method where skin units were buildable normally and the lizards were spawned might be interesting.
I haven't played Grigori in a long-ass time, so I don't know if they fixed this, but in the earlier versions of FFH the advenrurer mechanic didn't really work very well, because adventurers would be crowded out by other GPP types, either from specialists or wonders.
Is this likely to happen here? Or can they track adventurers/slann separately from normal GPPs?