Complex sentence: When the Cleric gives the Eradicator to Superman, he rapidly ages and dies as the link to the Eradicator extending his life is severed, Superman marking his grave with his symbol to reflect the impact the Cleric had on him.
Split into simpler sentences: When the Cleric gives the Eradicator to Superman, he rapidly ages and dies as the link to the Eradicator extending his life is severed. Superman marks the Cleric's grave with his symbol to reflect the impact the Cleric had on him.