How to calculate Ars Magica General spell levels

I had a query on two Ars Magica spells that appeared ostensibly to be doing the same thing, but have different final effects. From my first look it appeared one was incorrect in the final spell level. In fact both were right, but it took worked examples for me to understand it.

  • Paralysis of the Gift (PeVi20), from HP p.86. At level 20 it reduces casting totals by 10, R: Touch, D: Conc.
  • Belittle the Ferocious Warlock (PeVi20), from MoH p134. At level 20 it reduces casting totals by 5, R: Sight, D: Diam.

They are both using this PeVi guideline:

Reduce the casting total for all magic cast by the target by half the (level +2 magnitudes) of the spell. If 2 or more spells affect one target, only the highest has any effect: the penalties do not add. The spell must penetrate the target’s Magic Resistance in order to have any effect.

Why can two Perdo Vim spells be at the same level and have significantly different effects? Well, the trick  is due to the way the guidelines use the term “level”, and the way that the changes to Range, Duration, or Target are performed for general spells. The Paralysis of the Gift effect requires R:Touch which is slightly lower level, so more of the magnitudes can be applied into the core spell power.

e.g. breaking down the spells we get:

  • PotG = ((Lvl 20 – 2 mags for Touch/Conc) +2 mags )/2 = -10 mod to CT.
  • BtFW = ((Lvl 20 – 4 mags for Sight/Diam) +2 mags )/2 = -5 mod to CT.

Fundamentally the level is always the spell level the character is seeking to learn the spell at, and the guideline’s use of +1 mag or +x mags is where the adjustments for Range, Duration, and Target are applied. It would be clearer to say “chosen effect level”.

Hope this helps a little, writing it did.


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