Complex sentence: Grayson discovered that he was dying of a brain disease which left the rest of his tissues unharmed and bequeathed his body to Robotman to give him the possibility of a new life.
Split into simpler sentences: Grayson discovered that he was dying of a brain disease which left the rest of his tissues unharmed. He therefore bequeathed his body to Robotman to give him the possibility of a new life.