From Guild Wars Wiki
- Concise description
Monster cannot be attacked.
 Related skills
- This skill is a passive, continuously active effect, making it invisible to players. It is used by various NPCs that are not supposed to be fought.
- The description is misleading: This skill prevents others from targeting the NPC (with skills or attacks), gives them immunity to damage (including indirect damage, e.g. from AoE or reflective skills such as Retribution), and provides +20 health regeneration (that bypasses the normal +10 cap; the foe gains 40 health per second)
- Its targeting prevention also stops allies from being able to use beneficial skills on the immune NPC, e.g. allies could not use Orison of Healing.
- It does not prevent Life Stealing or the indirect damage from combining Illusionary Weaponry with skills such as Cyclone Axe.
- It is still possible to kill foes that carry this skill, although it is extremely difficult.
- One of many examples on YouTube of players killing an invulnerable foe.