Complex sentence: Surviving the incident, yet severely scarred, both physically and mentally, Rex learns from Mindbender and perfects the nanomites, using his own sister as a test subject in creating the Neo-Vipers as well as having a vendetta against Duke for leaving him to die.
Split into simpler sentences: Surviving the incident, yet scarred both physically and mentally, Rex learns from Mindbender and perfects the nanomites. He uses his own sister as a test subject in creating the Neo-Vipers, as well as having a vendetta against Duke for leaving him to die.