Lair
Lairs are specific areas within a zone that sport a higher density of, and harder, creatures.
The location descriptor will refer to the lair's name, but does not otherwise indicate that one is currently in a lair. The presence of strong creature packs and a treasure box is a good indication that you are in a lair.
Treasure
Treasure boxes appear in lairs. These containers are watched over by specific creatures or packs of creatures, called guardians. Defeating the guardian of a treasure allows Professionals to open up the box, usually revealing one piece of gear, and sometimes a fancy bag or a Puppet. Sometimes, if the guardian pack comprises multiples of the same creature difficulty, a second piece of gear is present in a box.
The last guardian of a Lair is usually slightly stronger than the rest.
Major lairs have a Legendary Guardian as their last - or only - guardian. Legendary guardians always guard three Artefact pieces of gear as a treasure. No Artefact Puppet or bag has ever been found[1].
Lair completion
When a Professional or a team has killed the last guardian of a lair, and enough of the previous guardians, the Professionals are notified of having "completed the lair".
Lair completion appears to be reliable only up to teams of six Professionals. If more than six people participate in the killing of the guardians, sometimes some of them do not get lair completion notifications[2]. Very large teams, such as the ones tackling Legends, are usually very lucky if they get more than two completion notices[3].
Professionals who have already completed a given lair do not get a new notification when doing it again. Those professionals still appear to count for tracking lair completion.
Gate enabling
The Gate crossing mechanics do not allow by default crossing a Gate into a new zone unless you have completed at least as many lairs in the original zone as the destination zone's tier. i.e. if you are in a tier two zone, and attempting to cross one of its gates to a tier three, then you need to complete at least three lairs in that zone.
Attempting to cross a Gate without the required lair count result in a descriptor notification:
| Tier N: destination | |
|---|---|
| Required: N zone lairs completed | Lair completion: M/N |