Complex sentence: In exchange for parole, Lucas clandestinely underwent an experimental procedure, originally intended to generate immunity to all illness; instead, it inadvertently granted him steel-hard skin and heavier, enhanced muscle.
Split into simpler sentences: In exchange for parole, Lucas clandestinely underwent an experimental procedure, originally intended to generate immunity to all illnesses. Instead, it inadvertently granted him steel-hard skin and heavier, enhanced muscle.