Smitty:
Ok, I'm not sure how to figure out required levels of magery or whatever for spells with the modifications for this game. Let's take Sandstorm, which I don't know what college it would be in either--it's Druidic PI4, or wizard magery 0 plus some spell prereqs. What level of magery or college skill do you have to have to take it?
Sandstorm might be either Destruction (it's an "elemental air/earth" damaging attack spell) or Conjuration (arguments could be made that it's "summoning in a sandstorm from somewhere"). The only requirement to cast it is that you take the required Path (and maybe Magery 1, Create Earth has Magery 1 as a prereq - Magery 0 is not required to cast spells in this game, it's High Mana).
So let's say bossman rules it's a Destruction Spell (that's where my money would go FWIW), it has 8 Spell prerequisites so unless you take it as a Technique and raise it, it will be -8 to your Destruction Path Skill to cast it (if it's Destruction).
Because we're usign the Ritual Magic system, you don;t have to learn individual spells, just the 'core' Path Skill, then all the Path Spells are defaults from it.
Now I don't know if Mad Mick is using the Simple or Complicated "Other Prerequisites" form, so you'll have to wait for him to answer that part. Simple form says if you don't have a non-Spell prerequisite (in the case of Sandstorm that's Magery 1) you cannot cast the spell. Complicated says for every full 10 points of missing non-Spell prerequisites, it's an additional -1 to cast (in this case not having Magery would add a further -1 to cast Sandstorm).
There are reasons for both forms, Simple is simpler, Complicated means
anyone can try to cast any spell. Complicated fits Elder Scrolls better than Simple... though... it will mean some spells get complicated (but this is PbP, so we've got time for figuring out the complex).
There is no Power Investiture available to PCs at this time as I understand it.