the game is, sadly, too easy. I really like the game, but i seem to remember it being pretty darn hard the first time through, with death getting summoned on me a lot as well as earth bore, but in my last 3 play throughs they were too easy. even the last mission was too easy.
my progression in the last one was S,S,P,P,C,C,C so my ultimate spells were death and intestinal.
in the last mission all i had to do was chain an abomination to each manalith, then summon a flying horror, target marduk first and after i fend him off once it's all over.
i keep looking for a difficulty setting but i don't find one.

I don't recall that there is difficulty setting in the whole game I think you are just set against a standard AI every time (possibly with handicaps and advantages for each mission). There might be different AI levels accessable in the editor, but even then you will be against hte best ai in the last missions.
Chances are that you have just managed to "Crack" the game workings as it were - since the AI will aways have a smilar fighting mechanic its possible to eventually come to a way of playing that will defeat the AI most times. And of course because the AI can't evolve and learn you will keep bashing them.
That is where most people jump to MP since people play differently to the AI and thus require a new set of skills to learn (infact in many cases a good AI beating player can be totaly defeated by human players because they are not used to opposing the different tactics used - also humans tend to use more "broken" combos where they can whilst the AI tends not to).
Ingame you might try making some custom maps with AI with advantages over you or seeking some out online. Also I think it might even be possible to edit hte actual campagne maps through the editor - I might be wrong on that, but if not then you can edit htem to give yourself more of a disadvantage and thus more challenge

That's the drawback of this game.
The game mechanics are such that the more souls you have over your opponent, the more difficult it is for your opponent to make a comeback.
At the start of the game, your opponent could actually kill you if it attacks with all high-level creatures with all it's souls, but it attacks with very few units to allow you to capture his souls.
During the first few missions you feel like you're accomplishing something, but it very quickly becomes apparent that the win is artificial.
As overread said, once you finish the single-player campaign it's time to move to multi-player. Single-player offers a branching storyline; multi-player offers strategic play. Even in multi-player, however, it's likely that the game is usually decided in the first full-fledged battle.
This isn't a Sacrifice-bash. I enjoyed the game for being different from most RTS games.

thank you for your replies, all
yes, it is too easy... i think i have figured out that all you need to do is survive the first rush to win. a large part of it is that the AI doesn't use magic well at all. it is VERY strange though, sacrifice is like a walk in teh park for me now... but i distinctly remember really having to struggle in it before, with death being summoned on me a lot and having to flee a lot.

I found the same. After a couple playthroughs, I found I could take on any number of teams in skirmish and win easily... It's a shame.