Grotto of Lost Souls

Grotto of Lost Souls is (originally) a level 65 5-man dungeon, later upped to level 70.

Grotto of Lost Souls was released in October 2018 (EU) as part Patch 75 NA: "Dark Reaches"/ EU: "Rising from the Shadows". Dungeon is know as "Lyan’s Underground Temple" in Korea, Lyan being Korean name for Leander.

When released dungeon was highest dungeon in game. Normal mode dropped materials to convert to Heroic Oath gear, and hard mode materials to enchant Heroic Oath to +2 and Transcendent masks.

GLS hard mode remained in game from April 2020 until January 2021 as higher mid-tier dungeon.

GLSHM is opened with patch v108 in August 2021.

Dungeon drops collection cards "Edwin", "Distortion Field" and "Kylos".

Lore
Dungeon continues Red Raiders story arc after events in Dark Reach Citadel. Upon reaching high enough Item level to clear the dungeon you'll receive letter from Hennika and she tells she can't handle Leander and Edwin herself. She asks to capture Leander and Edwin, for they defile the name of Red Raiders.

It's revealed Leander is now the leader of Red Raiders and Edwin is his puppet-master. Even Edwin is much more powerful, he is using Leader to achieve his purposes. Text in Card Collection hints Edwin is obsessed to "travel to other worlds."

In the Distorted Space behind teleporter after second boss Leander is now in middle of a ritual to summon another demon. Destroying the portal generator (takes one hit) stops the summoning. Frustrated by the failure of his plan, Edwin reverts to his true form: the dragon, Kylos. This causes horrible destruction and deaths. We see shadowy figure snatch Leander to safety.

After clearing the dungeon related quest has cutscene showing Leander facing his bother Elleon, who snapped him out when portal collapsed and Kylos awakens. Some hints of corruption happening to Elleon, possible caused by Killian, are given.

Note: name of Edwin is misspelled in quest text.

Bosses

 * Nedra, Man-Eating Plant (Orisk)
 * Ptakum, Executioner
 * Kylos, Odwin's True Form

Nedra and Ptakum are type "demon", Kylos "dragon".

Achievements

 * Normal mode achievements
 * You Rock! - don't take damage on rolling rocks on first boss fight
 * On the Brink of Death - defeat last boss without taking damage from semicircular strike
 * Inordinate Exsanguination - receive bleeding 10 times
 * Off to Slay the Dragon! - clear dungeon 10 times
 * Leander, I Got You! - complete previous achievements


 * Hard mode achievements
 * No Thanks, I Brought My Noseclip - defeat first boss without dying to wipeout mech
 * Talk About Anticlimatic - kill last boss within 8 minutes
 * Stomp Smash Smash Stomp - dont take damage from second boss smash attack
 * I Forgot My Safe Word - take 50 times electric shock in last boss fight
 * Just Another Demon and Dragon - complete previous achievements