Perception

Perception in LOR is calculated like any other skill.

Your perception modifier is equal to:

Wisdom Modifier + Perception Modifier Tier + Half Level

Passive Perception

Passive perception is used to calcualte stealth checks against you. It refere to your passive observation of the surroundings

Formula:

8 + Perception Modifier

Active Perception

Active perception is defined when a player is actively seeking something and is used like a normal skill check.