Simplify the following text for a Grade 10 native English-speaking person.
Original: During and after the war , he killed Priam , Eurypylus , Polyxena , Polites and Astyanax , among others , enslaved Helenus , and forced Andromache to become his concubine . The ghost of Achilles appeared to the survivors of the war , demanding Polyxena , the Trojan princess , be sacrificed before anybody could leave .
Simplified: He killed King Priam and Astyanax , sacrificed Polyxena to his dead father Achilles , and took Helenus and Andromache with him as slaves .