Sensus Magicus, Magic Sensitivity, is described briefly in the Core Rules (ArM5, 66). However, some detail that might be helpful in a Saga is lacking. For example, at what distance can sensitivity work? This Saga rule will re-state the Core Rules regarding this talent, adding some additional detail.

This Saga rule assumes that the Ease Factors described in the Core Rules function at a range similar to Touch - although the character may not have to actually touch the thing sensed, she must be able to do so (i.e. no more than about one pace distant from the character).

Thus, if the character is within a Magic Aura, the Ease Factor would be 12 - Aura strength. Similarly, if the character is within one pace of an enchanted item or active spell effect, the Ease Factor would be 21 - effect magnitude, and if within one pace of a magical being, the Ease Factor would be 15 - one-fifth the entity's Might (or, re-phrased, 15 - Might magnitude).

However, it may be possible to sense magic at a greater distance, albeit not as reliably. The following lists the modifiers for various ranges:

Sensitivity may also sense the presence of magical talents or the Gift, although this only indicates that someone is magical, not the specific details. Stronger talents are more easily sensed than weaker talents, as noted below. In all cases, note that only talents deriving from the Magic Realm are sensed; talents deriving from other realms are not "magical."

Use the lowest applicable Ease Factor from the list above: for each additional Minor Supernatural Virtue possessed, subtract 1 from the Ease Factor; for each additional Major Supernatural Virtue possessed, subtract 3 from the Ease Factor; for additional Supernatural Abilities, add all of the Ability Scores together before subtracting from the Ease Factor (and do not count Virtues separately if those Virtues also have Supernatural Abilities). Many Hermetic Virtues should count as Supernatural Virtues for this purpose; for Hermetic magi, add all Form bonuses to the modifier for Supernatural Ability Scores (this does ignore Technique Scores for this purpose). Most Hermetic magi, and many apprentices, will be very obviously magical to someone able to sense such things.

As with all magical talents, the Aura modifier applies; thus, it will be trivially easy to detect a strong magical aura, as the Aura modifier also adds to the sensitivity total; conversely, it will be more difficult to sense magical things within a Divine or Infernal Aura.

As noted elsewhere, sensitivity may also sense Familiar Bonds, as with other types of enchantments, using the Bond total to calculate the magnitude of effect.