"Regeneration"[note 1] is a process by which Doctor Ivo Robotnik was able to completely transform himself in the comic series Sonic the Comic. By encasing himself in a giant egg, Robotnik experienced a complete physical makeover, including both his physical appearance and his clothing. This even extended to the transformed Robotnik wearing gloves, whereas he had not been wearing any before.
The metamorphisis is apparently performed at will, but was used only once during the series, as a means of updating Robotnik's design from his original games design to the design of Robotnik from Adventures of Sonic the Hedgehog.
Apparently serving as Robotnik's image consultants, Thomas and Miller noticed that the people didn't like Robotnik and felt he should get a complete make-over. Robotnik kicked them out of his office for suggesting it (even throwing his phone and lamp at them as they fled), because as a merciless, power-crazed dictator he didn't care whether people liked him or not. Nevertheless, Robotnik decided that his current body had "served its purpose" and that it was time for a change, leading him to encase himself in a giant egg. He soon emerged, completely transformed and feeling rejuvenated ("more powerful... more deadly... more rotten than ever!"), although when Sonic saw Robotnik's new appearance he told Robotnik that he should "stop takin' those ugly pills!"
The process began with Robotnik generating a barrier around himself which quickly became egg-like and gave off green fumes. When the transformation was complete, the shell of the egg began to crack and Robotnik broke out, hatching in his new form.
While he had a new body, his signature traits such as his dark eyes, obesity, baldness and big ginger mustache remained. His bodysuit also changed during the process, but still retained its previous colour scheme.