In the middle of the third season in "Return to New York", tensions began to grow high within the Foot of their alliance with the Kraang, but Shredder convinced everyone that he will keep his promise to take the city back from them. After a feral Splinter was found by the Foot-Bots and taken before him, Shredder had Stockman-Fly work on restoring his memory, which is what April did instead with her Kraang powers when she, the Turtles and Casey Jones returned to the city to rescue their sensei. In "The Pig and the Rhino", Shredder sent a now mutated Steranko and Zeck (who are later renamed Bebop and Rocksteady by Michelangelo) to find Karai again, like they did recently before the Turtles helped her escape, or else they will be given something even more painful than mutation. After the Turtles unknowingly led them to her, the two succeeded in re-capturing Karai (while the Turtles were not looking) and delivering her back to Shredder, who promised to fix everything he had done to her. The Kraang invasion eventually came to a stop made by the Turtles and the Mighty Mutanimals, but its effects had eventually gave Shredder a gift for his cooperation with the Kraang, which shifted the balance of power within the city's criminal underworld over to the Foot. For him, this was achieved by gaining control of the Purple Dragons and other Asian gangs through Hun, several South American gangs through Fishface, the Russian mob through Rocksteady, and the Sicilian mob through Vizioso. By using this power, Shredder had these crime groups aid him with collecting various chemicals from a chemical company called Aumen Chemicals, an abandoned Kraang lab and Vizioso for a mind-control serum that he planned to create and use on the Turtles, the Mutanimals, and Karai.