Sensual acuity

The skill to perceive things, that are outside the usual or especially hard to perceive. For example everything that has been hidden, but also details in the landscape that would be lost on most others. Bonuses for example in familiar terrain or because one counted on things being hidden. It's a lot easier to find the secret passage out of the ruin, if you know there is one and are actively seeking it.

The starting value is: 25 + 2 * (P + I)