Mm... while I'm thinking about it, some thoughts on breaking R'lyeh, from my perspective of things, since it was talked about earlier.
Probably the biggest thing with R'yleh is that they have one absolutely
tremendous weakness -- they're
incredibly dependent on their capital. Primarily because of their caster starspawn, which is their number one bottleneck for force projection -- even with recruiting one every turn I could, gold and other situations allowing, I had all of fourteen total by the end game. Without those, my best recruit (which frankly feels freakishly overpriced, for what it is) caster is
2S, without boosters, and that's a 1/4th random. You can do some battlecasting with that (especially if you get around to using communions in conjunction with the much more easily massed star children), but when it comes to forging, mobility, and astral artillery rituals they're basically junk -- can't even forge boosters for themselves. Slave mages... aren't worth talking about. If r'yleh is seriously recruiting those, there's good odds they've already lost
That's hyperbole, but... only mildly. They really are incredibly terrible, especially for their cost.So there's two things out of that -- if you can stop the capital from recruiting (either by siege or unrest), or kill those caster starspawn, you effectively cripple R'lyeh. Them being underwater makes either of those harder, but there's a lot that can be done. For Jotulmdel, dropping a crap ton of blights (Alt-4, 2E1D -- might have required a death empowerment, but probably would have been worth it) on my capital would have murdered me -- I had also spent every turn since seeing the earth king dreading the beginning of an unending earth attack barrage (and expecting to have to teleport my everything out, but even that would be a notable victory for opposing forces). Anything in general that bumped unrest or caused assassination attempts, if it could reach underwater, would have been nasty, to say nothing about just biting the bullet and loading up a (few) commander(s) with waterbreathing and MR boosting kit and setting them to siege.
Other stuff: You basically
have to make R'lyeh fight for the water. If they're not keeping raiding or invasion down, they are -- as Jotulmdel probably noticed -- free to drop astral artillery all day and use the nasty raiding potential of well positioned UW provinces to wreck all sorts of havoc. Skratti or Carrion Lords would probably have been ideal for this: One with a waterbreathing ring, maybe a fire brand and vine shield, would have been a threat. Two or three, with one (maybe with a booster, or just carrying the appropriate item) doing something like casting friendly currents or some buffs on the other(s), would have managed to cut a path through a great number of my provinces and possibly a couple of the larger armies.*
Other bit of advice would be MR kit -- for the love of zeus, if R'lyeh has reached soul-slay mind hunt,
MR kit. That was another consistent surprise, I'm guessing brought on by gem income limitations? But stacked up MR would have made a
serious difference. Is how you make an astral ritual spamming R'lyeh (or anyone, really) uneconomical and effectively win the war against them off the battlefield (on it, too, to a large extent, but especially off it).
Another niche possibility is hitting supply -- pillaging when you raid, dropping any ritual spells you can spare that kill population or shift the scales to cause supply hits, that sort of thing. R'lyeh's armies are incredibly supply hungry, and it's very easy to push them over the starvation point (and from there, hit their morale in battle and send them running).
The mindless thing is also a pretty big deal, though hard to exploit for a while. Golems are the big late-game weakness, but if you can squeeze out the gems and casters for it, earlier stuff like gift-of-reason'd Crusher Constructions (with some mindless troops, probably) are
very possible and pretty capable of no-selling quite a lot of what R'lyeh brings to the table.
... anyway, that's most of the $0.10 I can recall off the top of my head, when it's approaching midnight. Raiding, stop the caster starspawn, if you have earth attack and blight (or a
anything like them) abuse the buggery out of them (incidentally, the beginnings for a dedicated blight (and eventually, raging hearts, among whatever else could be scraped together) assault on Jotulmdel's lands was probably going to kick off within a turn or two), and MR boosting equipment. That's about it.
*It's an aside, but the overall lack of skratti kinda' surprised me. Did notice some being used against gman's group, but I was expecting them to be
everywhere -- they're very solid thug/minor SCs and ridiculously good for raiding via the wolf form.
E: And ah, part of that jump was also me turning over some provinces, apparently -- you can see r'lyeh's income drop during the same period. Shy of half, but not by too terribly much.