Complex sentence: Unbeknownst to Invincible, Levy survives the explosion but was horribly mutated and suffered internal organ damage all while believing it was Invincible who stopped the machine.
Split into simpler sentences: Unbeknownst to Invincible, Levy survives the explosion but is horribly mutated and suffers internal organ damage. Levy believes it was Invincible who stopped the machine.