Sewers of Nihilia, Lair of Trapped Ones

Overview

This instance is reached by speaking with High Priest Diru Riwirn in Barindu as the third step in progression. If you have already completed it or wish to go for xp and random drops you can tell Gamesh "lair". The walkthrough below is for the progression version. For the Gamesh version you can simply do as you wish.

Mobs in the zone range from 60-64 hitting as high as 900. In addition to the 3 loot dropping rares there are two zonewide drops Larva Skin Cape and Taelosian Runed Girdle.

When you get the instance from High Priest Diru he gives you Seal of the Nihil High Priest. Once inside the zone start making your way to the northwestern chamber to find Alej Leraji trapped by rocks. Hand him the Seal and he will tell you that he needs his stone shaping tools to escape. This starts a 60 minute clock, if you aren't done by then you fail.

You need to clear out mobs in three areas in any order:

The emotes do not yield actual items. Once you've triggered all three return to Alej and say "I have found your three stone shaping tools". This completes the expedition and gives a character flag.

Rare Mobs

Rare mobs do not spawn until you have killed at least 20 mobs. This is to prevent people from simply spawning instances over and over. All three rares drop Oiled Cog for Breakdown in Communications quest.
Blistering Larva
Rare worm. Hits upward of 1300, but no abilities.
Drops - Sodden Turepta Hide Boots, Jagged Stone of Hatred, Polished Gem of Curiosity
Rigara the Lost
Rare ghost. Hits upward of 1300, but no abilities.
Drops - Grimy Wristbands of the Scribe, Cracked Geomancer's Talisman, Pockmarked Aegis
Sludge-Eating Fly
Rare fly guy. Hits upward of 1300, but no abilities.
Drops - Pitted Vambraces Stonemite Carapace Mask Crackled Gem of Quickness