Complex sentence: Madam Slay was a lover and ally of Erik Killmonger, she had the ability to command leopards, and was using them to slaughter leopard hunters when she first encountered the Black Panther.
Split into simpler sentences: Madam Slay was a lover and ally of Erik Killmonger. She had the ability to command leopards, and was using them to slaughter leopard hunters when she first encountered the Black Panther.