Just an update to the Magic Resistance rules. I was struggling to come up with a mechanic that worked like the classic "Save for Half Damage" under my very different damage system. I think this fits the bill... New rules in blue.
This describes how targets of the spell can attempt to resist it. Most Resistance tests are one of the three main Defense Tests: Speed, Mind, Body, or combat defenses like parry and dodge along with Toughness.
Spells that cause reduced damage mean that the target subtracts the amount by which they pass their defense test from the damage. (If the target gets an 18 on a Speed Test 16, they subtract 2 from the base spell damage, but still must take the damage.)
Alternatively, a spell may always produce a minimum effect, even on a successful defense test. This may either be a base wound level, or another temporary or permanent effect, like, “stunned for 1d6 turns,” or “Blinded for 1 hour.”