Frostbite

S1, E6: Rex pushes himself too far and must be airlifted to a remote Providence facility to have his surplus nanites offloaded into a containment unit. When he wakes up from the dangerous procedure, he finds himself all alone...until The Pack shows up. Turns out the shifty director of the facility is selling Rex's nanites to none other than Van Kleiss. When the scheme is uncovered, the dirty Providence scientist creates an explosion of nanites that turns him into an evo even Rex can't stop.