The Perdo Corpus guidelines state:

Level 5: Do superficial damage to a body (for example, remove its hair).
Level 10: Cause a person pain, but do no real damage. Cause the loss of one Fatigue level.
Level 15: Do one Body level of damage to a person. Destroy a person’s limb. Destroy a corpse.
Level 20: Destroy one of a person’s major senses. Do two Body levels of damage.
Level 25: Age someone five years. Do three Body levels of damage.
Level 30: Inflict a major disease. Do four Body levels of damage.
Level 40: Kill a person.

My character is interested in creating a spell that does multiple levels of fatigue instantly rather than Body damage levels; do they scale up as per the body levels?

So Two Body Levels == Three Fatigue Levels?

We're playing Ars Magica 4th Edition

  • 2
    \$\begingroup\$ Incidentally, don't forget that a low level 'cause one fatigue level' can be easily and quickly mastered, whereupon you can multi-cast it and target the same target multiple times or multiple targets. This is more flexible than different spells for each situation, or one big spell that does everything. \$\endgroup\$
    – Mark Booth
    Jan 20, 2015 at 19:13

1 Answer 1


As a general rule, (at least in 5th, but to my knowledge this hasn't changed) +1 magnitude increases the "damage" done by one "step." This is similiar to how PeCo does direct damage, and how the target guidelines for calculating the base size of something (or increasing the complexity of the effect) are calculated.

Thus, a +5 damage CrIg "here, have some fire, my treat." would take +1 mag to be +10 CrIg "here, have more fire."

The rule I used for making a "fatigue poison" was to cost fatigue levels in the same way. So, base 10, +1 mag for 2 fatigue levels, or a whopping +4 mag for "you go sleep now."

Since 10 +4 gets you a level 30, the critical thing is to look at other level 30 guidelines and see if it's in the same ballpark. Since level 30 is the equivalent of an "incapacitating wound" which will remove someone from combat, I see nothing wrong with this parity.

  • \$\begingroup\$ That all makes sense to me - thought it would be something like that, cheers! \$\endgroup\$
    – Rob
    Jul 2, 2013 at 6:16

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