From Guild Wars 2 Wiki
Hint: Use the Gloominator to capture the gloom while in Tequatl's watery grave.
— In-game description
- Use the Gloominator while submerged by Tequatl's Watery Grave attack. This is an AOE attack, usually situated within melee range, that is usually launched when Tequatl loses one-quarter of his total Health (i.e. at 75% Health, at 50%, and at 25%).
- It is often rare for Tequatl to actually use this attack, as a large player army will keep him stunned throughout the phases where he would use it. Watery Grave is still placed at the 75% Health transition, so watch for it carefully and be ready to enter it.
- Players can also access the Watery Grave after the fight is over. An underwater entrance is located directly west of the chest, against the underwater drop-off beside an NPC Krewe Researcher.
- There used to be an area that constantly applied Watery Grave; it was eventually fixed in a patch.