(Ἰλίωνα), a daughter of Priam and Hecabe, is not mentioned by the earlier poets and mythographers, but the later ones relate of her the following story. At the beginning of the Trojan war her parents entrusted to her her brother Polydorus, for she was married to Polymnestor or Polymestor, king of the Thracian Chersonesus. Iliona, with more than sisterly affection, brought up Polydorus as if he had been her own child, and represented her own son Deipylusas Polydorus. When Troy was taken and destroyed, the Greeks, desirous of destroying the whole race of Priam, promised Polymnestor a large sum of money and the hand of Electra, if he would kill Polydorus. Polymnestor accepted the proposal, but killed his own son Deipylus, whom he mistook for Polydorus. The latter thus escaped; and after having subsequently learned Polymnestor's crime, he and Iliona put out the eyes of Polymnestor, and then slew him. This legend was used by Pacuvius and Accius as subjects for tragedies. (Hyg. Fab. 109, 240; Horat. Sat. 2.3, 64; Serv. ad Aen. 1.653; Cic. Ac. 2.27, Tuscul. 1.44.)
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890