Ekthul, Wormfeast, is a unique Grotesque found in the Abandoned Cellar in Stinging Winds, Act II of Diablo III. It spawns for an unmarked event.
Upon entering the far room of the cellar, peasants held prisoners will warn the player not to come any closer. If player(s) choose to come towards them anyway, Ekthul will spawn along with several Dark Cultists. Upon their death, peasants will tell that Coven was using them as a bait.
In combat, Ekthul has Plagued affix, and spawns several spiderlings upon death.