Being in Siege state applies the following effects:

・Damage to HP and CP will not be taken when in effect
・Increases ATK and MATK by 100%
・Nullifies status ailments
・Nullifies special status ailments
・Nullifies debuffs
・Nullifies special debuffs
・Vital Strike (10% chance to increase damage dealt by 50%)
・Removed after receiving a set amount of damage (300% of max HP excluding buff and field effects)