I've started a rogue-cleric (yeah!) with the Earth and Death domains. I picked Earth for Stoneskin, and Death for the sheer coolness of having a Lawful Good cleric summoning a Chaotic Evil shadow slave. (Always more fun to tease my enemies.)

But a basic question: will this summoned shadow ever become strong? The domain description claim that it'll increase in strength as I ascend the level ladder. Right now I have six cleric levels and I'm none too impressed. Will this shadow ever be useful for anything besides mocking? Or will he always be merely a shadow of the shadow of his former self?

The shadow is a shadow of a shadow of a decent shadow summon, and will stay that way.

I once selected the Death domain for the same reason. What i found was that the shadow really isn't the greatest summon out there. In fact, it has a level cap of lv 10 (maybe 15 its been a while), even if your cleric is at lv 40. Its final incarnation is that of 'shadow lord' and aside from its resistances, it is weak both in health and attack power. Still, for a low level game (like SoU) it may be useful.

The shadow is not the greatest thing - like many of the features of NWN, I think it is there for roleplaying flexibility, especially in online play so that you can customise your character. I put it in the same bucket as the Badger animal companion. It's useless really, but if you wanted to have a Badger loving Ranger - then it's available for you.

I'm playing HotU, so it seems that the shadow's utility will, alas, remain nil. But I'll keep it for the sheer joy of summoning a helpless evil critter and forcing him to suicidally rush the enemies. Like the way you could force that one evil fella in Planescape to sacrifice for you. Just call it "The Charge of the Dark Brigade"!