Precision & Penetration

[JonBrave]

Do I fully get these, or don't I? I have read the manual and stuff, but not sure whether all has sunk in.

Precision is about increasing the chance your thingie hits the chosen target. Penetration is about how much effect/damage it does when it arrives wherever it arrives. Right?

Then both of these come into effect both with spell casting (battlefield and ritual) and with archery (and lightning). Spells tend to be Astral and against MR. Arrows go against Protection (with some shield). Melee has nothing to do with either (but what about those adjacent spells like Hand things). Right?

I think I know Precision 100 never misses, so no point boosting in that case. There's something in the manual about an MR die roll where it says +10 but it's +12, which might involve them.

Is there much more than that to say? I don't have a feeling for the figures, not sure for example whether a spellcaster needs boosters for either or what it's worth for a slot, that sort of thing.

If anybody feels like summarising What Dumnmies Need To Know About Precision and Penetration here, that would be nice...