The max time Evasion lasts is for 8 seconds, with 120.0 Bushido/GM Parry/GM Tactics. Evasion has a cooldown timer of 20 seconds, making it to where there is at least 12 seconds when the Samurai is vulnerable to spells.
Evasion allows you to block direct damage Spells and Spell-Like abilities, like Dragon Breath (It will not block status spells such as Curses, Mana Vampire, Poison, Strangle, etc, but it will block the damage from Bleed/Poison/Strangle ticks), it increases your chance to block any attack by 50% of what it normally is, with 120.0 Bushido/120.0 Parry and 80+ DEX, your chance to block with a 2 handed wep is 40%, it increases to 60% when Evasion is active. Archers cannot Parry, thus Evasion is useless to them.
I find it funny how Mages moan and gripe about Samurais using Evasion to block there spells, when Mages have always been able to dodge a Warrior's weapon attacks with Wrest, and a Warrior was never able to Block a spell prior to SE, they could only lessen the damage with Resist skill prior to AoS. I find it really funny when it's a Parry Mage that is pancakes about Evasion, considering not only can they dodge a warriors attack, they can also block them. A Mage's defense against Warriors is always up (Unless they're using a weapon and get Disarmed) when a Samurai's defense against Mages can only be up for 8 seconds out of 20 at max. And let's not forget that before they added the Tact/Weapon skill requirement and Timer for Evasion, the greatest abuse of Evasion was by Parry Mages with Bushido who could keep Evasion up constantly, they were practically unkillable.
