Originally Posted by FlowerofSpeech
The best way to think of evasion is "x% to NULL damage" the word evasion sort of makes it more arcane than it really is.
I disagree; Evasion *is* a little more complex than that. It not only nullifies the damage of an attack, but also any effect it may have (Bash, Poison, Slow, Purge, whatever). This makes it (in special but numerous situations) anywhere from marginally to exceptionally more useful than armor.
I would suggest adding true damage-negation abilities (% chance to receive x or x% less damage from an attack and/or spell) to this guide as well, but what do I know.