Avoid redirects here. If you were looking for the order 'Avoid' from FE9/FE10 then see Order#Avoid
Evasion determines a unit's ability to avoid enemy attacks. Faster units such as Assassins tend to have a higher ability to evade attacks, whereas the slower units like Knight and General typically have a lower ability to evade attacks, but higher Defense.
In most games, evasion is affected by Attack Speed X 2 + Luck. But it can also be affected by Supports, the Weapon Triangle, Terrain Bonuses and low Con. Also, in the games featuring Biorhythm, it may also change slightly.