The Sandworm Lair is a second-tier zone on the far western shore of Maj'Eyal.
The Lair consists of small, round, disconnected open rooms. These rooms are the only "stable" parts of the level. Peaceful, invulnerable sandworm tunnelers constantly roam the level, moving from room to room, and leaving trails of unstable temporary tunnels behind them. If the player or any entity other than the tunnelers are caught in a tunnel when it loses stability and caves in, they will take a substantial amount of physical damage and begin to suffocate if they need to breathe.
The mini-map will show stable squares in black (once they are lit) and unstable ones in blue. The player is expected to follow the sandworms to get to the rooms; teleportation is also an option. Entering a tunnel without knowing how recently it has been dug is very risky and not advised. A high light radius and/or some means of illumination is very helpful here. It is also possible to partially direct the tunnelers by body blocking them from moving in unwanted directions. There are always 10 stable chambers per level.
In addition to the tunnelers, the zone is inhabited by hostile sandworms, jellies, and other monsters. Beware the sand drake's blinding breath and the gravity worm's pinning gravity field. There are also several "glowing chests" on each level, which may contain random artifacts of any tier. The boss is the Sandworm Queen. She can use Sand Breath as well as summon a host of additional sandworms to aid her. Her heart is a guaranteed drop that can be consumed to grant 3 stat points, 1 class talent point, and 1 generic talent point, as well as upgrade the Harmony or Vile Life talent tree (see Heart of the Sandworm Queen for more details).
After returning from the Far East, the backup guardian of this zone is a Corrupted Sand Wyrm on the top level. There will be no tunnelers at this point; they have all been devoured by the Wyrm. The Wyrm will immediately begin to seek out the player upon entering the level, so one should be prepared for a fight as it bursts through a wall. This boss drops a Wyrm Bile potion which gives random stat increases/decreases (-3 to +6 in each of the 6 stats) and 1 talent category point. Consuming both the Heart of the Sandworm Queen and the Wyrm Bile satisfies the "become close to the draconic world" prerequisite for applicable prodigies.
This zone has an alternate layout consisting of only 2 floors, where the top floor is inhabited by extra large tunnelers that constantly spawn near the entrance of the top level and travel towards the exit to the next floor.