 In "Into Dimension X," the Kraang have finally perfected the mutagen, but the Turtles were secretly warned about this success by Leatherhead through a Kraang Communication Orb.After finding their way into Dimension X and traveling to the Kraang's home fortress, which was being guarded by Traag and Granitor, the Turtles rescued Leatherhead and helped him stop the Kraang from dumping the perfected mutagen into Earth's dimension through multiple portals.In "The Invasion," the Foot Clan finally made a full alliance with the Kraang to draw out and destroy the Turtles in exchange in helping them invade the city, which the Kraang did through various spies; the character Irma Langenstein is discovered to be the robotic housing of one such spy, Kraang Sub-Prime, who was eventually defeated by Splinter.