Wiki - Legendary Spawn & Artifacts
In Felucca, one in 100 creatures will be spawned as a Legendary with the chances increasing as the type of spawn becomes more powerful. These advanced spawn are much stronger, faster, and more powerful than their non-legendary versions. The best advice you can get when dealing with Legendary Spawn is to be careful until you know what you can handle.
Defeated Legendary Spawn have a chance of dropping a Legendary Chest on their corpse, or the player who dealt the most damage to the spawn has a chance of a Legendary Artifact dropping in their pack. The more Fame the spawn has, and the more luck you have, the more likely each will occur.
Players can preview Legendary Artifacts in the LoS Display Gates area, which is accessible on the World Teleporter under Custom Locations.