[Tuidjy]

If you have a problem with massed troops who mind blast you, use ranged units
set to "fire archers" to shoot them to pieces. Their meat shields are nothing
to write home about.

If you are having a problem with their mastery of astral magic, it's hardly any
different than other astral races.

If you are having problems with going after them underwater, the solution is the
same as with any other water nation - keep them off the dry lands, and eventually
overwhelm them with your much higher magic gem income.

If you are facing a competent player, and thus having a problem with all of the
above... well, that's the way of Dominions. R'lyeh is a very good race, probably
one of the best in the Late Era, and no slouch earlier.