Gravesludge

This opponent resides on the Siren Isle in a deep cave filled with massive amounts of slime, toxins, and anomalous creatures. To start the fight, you need to trigger the "The Drain" event using the Siren Isle Command Map or wait for someone else to do it. After that, head to the coordinates: /way 62.75, 75.25. You’ll find a deep cave, the entrance of which will gradually be breached by goblins using explosives (red-colored bombs). Once the grate is destroyed, descend, and inside the cave, you will encounter this radioactive creature.

Respawn:

10–15 minutes, but the creature will only appear if the "The Drain" event is triggered. This information is verified for the current version of World of Warcraft: The War Within (patch 11.0.7.58238).