In the climax, Rex uses the master control to send out a worldwide "cure" command, effectively curing every E.V.O. (Exponentially Variegated Organism) on Earth.
Rex must face the Consortium in a final showdown to decide the fate of the world. Plot Summary Generator Rex - Season 3Eps19
To defeat the Consortium and fix the world, Rex must risk losing his memories again, as he has to access the master control code within himself to shut down the Meta-Nanites. In the climax, Rex uses the master control