Simplify the following text for a Grade 15 native English-speaking person.
Original: The emperor now changed his name to Lucius Aelius Aurelius Commodus and , at 29 , took over more of the reins of power , though he continued to rule through a cabal consisting of Marcia , his new chamberlain Eclectus , and the new praetorian prefect Quintus Aemilius Laetus , who about this time also had many Christians freed from working in the mines in Sardinia .
Simplified: Commodus continued to rule through a cabal , which now consisted of Marcia , his new chamberlain Eclectus , and the new praetorian prefect Quintus Aemilius Laetus , who about this time also had many Christians freed from working in the mines in Sardinia .