Wondering if this is possible (rituals)
 

I'm wondering if it'll be possible to add some sort of effects to spells so that a happens if it succeeds and b happens when it doesn't?

As an example, let's say you have a "ritual-blocking" enchantment over a province that has a 1/2 chance of stopping inbound enemy rituals. Now, I want to cast a ritual that costs 2 earth gems and 1 astral pearl. If the "ritual-block" stops the spell, I lose both the earth gems and the astral pearl. Otherwise, I keep the astral pearl.

I could think of a few interesting possibilities with such a system. Such as "you'll need an astral pearl as well as the fire gems to cast Oven in the Sky. Should it be reflected, the caster's province will be affected and the astral pearl will be consumed by emergency production of magical sun lotion".

Re: Wondering if this is possible (rituals)
 

No spell required two types of gems in DomII.

There are no rituals with a mechanic similar to that in DomII, but there is at least one combat evocation - Petrify kills if it gets through magic resistance, paralyzes if it doesn't. So I think it IS possible to have rituals with varying effects. I don't know if there will be, of course, but I think it'd be possible.