Traag is a towering being from Dimension X, who is one of the six Cosmic Monsters. He is the first creature The Kraang bring to Earth through their inter-dimensional portal. He is twenty feet tall, his body is made of stone and he spews molten lava from his mouth.
Traag is the first creature that comes to Earth after the Kraang reactivate their Trans-Dimensional Portal, located in TCRI. His body is made of stone that is so thick and strong that one of Leonardo's swords broke upon trying to strike him in the leg and he spews lava from his mouth. The Turtles tried to fight him, but he was much too huge and powerful. It took the combined force of Leatherhead and Donatello's homemade explosives to bring him down, but Traag simply put his broken body back together. In the end, Leatherhead was forced to drag the giant alien back to Dimension X to save his friends.
He appears guarding the Trans-Dimensional Portal, Leonardo blasts off his arms and legs to distract him as Donatello disables the shields.
Krang and Shredder open a portal to Dimension X and bring Traag and Granitor through along with many smaller rock monsters. It seemed that the rock monsters would win, however Bebop and Rocksteady had a change of heart and helped the Turtles, their counterparts, and the Mutanimals take on the rock monsters. The Turtles blasted missiles from their vehicle at the duo, scattering them to pieces and banishing them back to Dimension X.