On the subject of C'tan/Yngir and Eldar gods, repost from earlier necron thread:
The Eldar Pantheon is divided into Gods, and the Yngir, the daemonic gods who serve Khorne, who is both god and Yngir (Note: Yngir has linguistic similaries to the term "Eladrith Ynneas" (Meaning "Dark Eldar"), the Dark Eldar realm of Ynnealidh ("The Necropolis Below") and the Eldar death dod Ynnead. It's quite likely Yngir as a term has connotations of death and darkness)
Now, Khaine's war against Isha, Kurnous, Vaul and the eldar is obviously a parallel for the Old Ones war against the Necrons and the C'tan.
Khaine's servants are described in one myth as being the souls of the dead, crammed inside suits of armour, to keep fighting eternally.
Khaine is noted to have won the War in Heaven, as are the Necrons.
Then, with the Eldar gods/Old Ones nearly destroyed, the mysterious entity Cegoragh, the Lauging One, who has many similarities to the Yngir labled "The Jackal God", engineers civil war on the Victorious Necrons. Pitting C'tan against C'tan, and convincing the Silent King that the C'tan will then turn on him.
The Necrons then silence the C'tan, and the Yngir "Khaine"/The C'tan "The Burning One", hoping to escape the wrath of his servents, who have now turned on him, sides with the Old Ones/Eldar Gods, even shattering Kaelis Ra to prove his worth to the sundered Pantheon, and hiding in the Webway, the Realm of the Eldar Gods, and the place he once threw open the gates to.