Armor-ignoring damage
From Guild Wars Wiki
Armor-ignoring damage is a property that damage can have. Such damage deals the same amount of damage regardless of armor level. In addition to skills which specify that they are armor ignoring, most skills which do not specify a damage type deal armor ignoring damage. Bonus damage from attack skills are always armor ignoring.Armor ignoring damage also ignores character level, so a level 1 character using an armor ignoring skill will deal the same amount of damage as a level 20 character with the same attribute rank.
Unlike health loss and life stealing, armor ignoring damage is affected by damage reduction.
Mesmer, Necromancer and Monk skills often deal armor ignoring damage.

