[Aleph]

I prefer LA, myself - all the same units, but now it's crazy time. If you think it's hard trying to break into a water nation from land, now try doing it when you're insane. So a lot of this is derived from LA strats, and they may not work as well.

1. Basic underwater expansion strategy is a large mass of lobo guards (50-100, set to hold and attack) backed up with maybe 10-20 Illithids. You're the only party with ranged weapons under water, so you paralyze a good chunk of the enemy before your cheap disposable meatshields swarm all over it. You can vary the mix of Illithids/Lobos - a single Illithid costs the same as 10 Lobos, so fiddle with it and see how comfortable you are with Lobo losses vs. high commitment of gold.

2. Voice of Tiamat is a good early research priority, along with Haruspex and dark knowledge (water/earth/nature/death seem to be the most common underwater sites). You can use a Slave Mage with a couple boosters to cast Contact Naiad, and she can kick off a clam based economy for you. This is of vital importance for LA, when you need to fund the switch from Starspawn to Void Spectres as your people die off. However, I'm sure you can think of some good things to do with your pearls (late game, communion -> mass enslave is a nice gamewinner, but there's a lot of time to kill before you can do that).

3. Pretender design - I'm pretty bad at pretender design, and most of my experience with Rl'yeh comes in the late age where it's much more important to go Turmoil/Luck/Growth due to your dwindling population. It might also help to know what nations your opponents are playing, to know if you need massive Astral power just to be safe. I often just take massive Order/Growth/magic scales to be safe with most non-blood non-lethal domain nations.

That said, a sleeping Void Lord with strong Astral (comes with the package, take at least 5-6 to be safe), Death (5), and Water (4) skills and dominion 9 makes a pretty tough contender due to his combo of life drain, fear (bonus from death gives him +10), awe, chill of winter, soul vortex, and astral shield. Hook him up with a Robe of Shadows, Luck Pendant, and a mix of resistance/regeneration/reinvigoration items (can never have too much) and he's a bad dude.

You can pay for him with a variety of options. If there is a lot of water (and you'd best hope there will be) then Cold 3 is a nice pick, since it has no effect under water besides making your Chill of Winter more effective. Sloth 3 is also a good option, assuming you're going to go for lobo guards / shamblers with Illithid backup rather than Meteorite Guards.

4. Raid, raid, raid. The single most important advantage any underwater nation has is the ability to raid from relative safety. You'll have to vary land tactics, since you are not longer the only ranged unit out there, and you may want to invest in some moderately armored troops just for that purpose (or you could grab another big chunk of Illithids to blast enemy archers - again, LA strat, since LA has so many freespawn needing to die that I never buy any soliders save for Illithids). Where possible, make a special priority of raiding lands that allow for Shambler purchases - but then again, it's nice to have a predictable raiding pattern so you can break it.

That's all for me.