Typically used with: Agility.
In short: get out of the way. Those who excel at Dodging are rather difficult to hit. Every incoming attack a character notices can be thwarted with a successful Dodge check. Less agile combatants may instead elect to evade attacks by parrying, but not all dangers can be smacked away with a weapon!
When another combatant attacks you, and you see it coming, you have a free chance to defend yourself. Even from arrows and fireballs. See the Defending section of Chapter 10: Combat. Your enemy rolls an attack, and you make an Evasion Roll, which is either a Dodge or a Parry. If your Evasion Roll meets or exceeds the Attack Roll, the attack misses.
If you have gained the prone condition or the grabbed condition, you take a −4 penalty to Evasion Rolls. If you have gained the wide-eyed condition, the immobilized condition, or the unconscious condition, you automatically fail Evasion Rolls.
Characters who fail to remove themselves from harm's way need to roll a Guard check to see exactly how much hurt gets laid out.
The GM can institute a DL for a danger that has no opposed roll, for instance, a collapsing ceiling beam, or arrows from that devious trap you just triggered. If you can't get out of the way, it could mean you have to roll a Guard check to determine the damage done. A hazard could have other effects, like a deadly poison, a stream of corrosive acid, or it might just kill you outright.