Hiidrala planned to give the second piece of the Heart of Darkness to Fugitoid and the Turtles if they prove themselves worthy to the Cthugga which obeys Hiidrala's every command. When Armaggon hijacks the Ulixes, the Cthugga deems them unworthy. After the Daagon soldiers arrived upon answering the distress call for the hijacking, Hiidrala is displeased that the Turtles failed the test and let their ship get taken over.
During the fight between the Turtles and the Daagon against Armaggon, Lord Dregg, and the Vreen, Leonardo rescues Hiidrala as she summons the Cthugga which manages to grab and swallow Dregg and Armaggon whole. Back where Cthugga is slumbering, the Hornetron, arrives and launches dozens of Vreen eggs into its mouth. Soon, the guardian opens its mouth to release the hatched drones, who escape with Armaggon and Dregg in tow. As Cthugga retreats deeper into its lair, Lord Dregg and Armaggon escape.
- Cthugga's name is an allusion to Cthulhu.