In some way, the outcome is still easily predicted: The players win. Because if they don't win 90 % of the time or something like that, you get very short campaigns and lots of TPKs. But how they got there, and what happened along the way, is not so predictable and can be interesting. (Unless you game doesn't consider positioning, weapon choices, powers, spells, environment and so on, but then it's probably not complex. Unless it is is, and then you might have made a mistake?

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So, what makes your crafting or ritual casting complexity actually interesting? Where do the player choices come in?
I am not really familiar with that many crafting systems or ritual systems from RPGs.
But things that come to mind:
Obviously, for crafting and probably rituals, you might want to think about the ingredients. But if ingredients are just a check-list, it's not that interesting. So, make ingredients mean somthing - change the outcome of the crafting or ritual, perhaps? Or at the minimum, some ingredients might allow you to shore up on weak spots in your crafting or ritual casting.
Say, to cast "Consult Mystic Sages", you need to make 6 checks, if you have 3 or more failures, you lose, and the more successes you have, the more detailed and precise your reply will be. Maybe they won't answer in riddles even!
The checks are on Arcana, History and Persuasion. But your mage always slept through history classes, all those dates and boring kings and queens and senseless wars were so boring! You're also not very charming, truth to be told. So what can you do?
Maybe you're a bit into blood magic, and can ritually cut yourself to reroll a check? (or sacrifice a lamb, but it's so cute, you can't do it!). Or maybe you can go a bit riskier, try to focus more power, that makes your Arcana check harder, but you got expertise, so you can risk it. Or maybe you could get some crushed diamonds as power boost?
Or alternatively, you could try for some bargain - reveal a secret to them they don't know (and is sure to land in the hands of your rivals and enemies at some point), or offer a favor?