Some of this lore is pretty funny (NOT!)

[quote]After one too many cocaine-and-alcohol-fueled underage orgies, the fabric of the Warp tore open and created the unstable phenomenon known as the Eye of Terror. It also wiped out majority of the Eldar race in a sex-fueled explosion and birthed the fourth major Chaos god, Slaanesh, the Prince of Pleasure.[/quote]

That's one way to die though