The default explanation is right there in the ability text: “you nimbly dodge out of the way of certain area effects.” However, that never quite fit the picture in my head. Leaping away from explosions and action-rolling like Indy are perfectly cromulent, but both maneuvers require you to actually move. The rogues of the world dodge in place, taking not so much as a 5′ step to get clear of danger. It’s like the end of Duck Dodgers, with world-shaking fireballs conveniently missing the plucky protagonist.
I’ll be the first to admit that this is a bit of a non-problem. Evasion is a fairly straightforward ability after all. But in the interest of making amusing headcanon, how do you like to describe/explain evasion? How is the rogue standing at the bottom of the crater while everyone else is roasted?