Basically, the highly psychic eldar empire became completely consumed by hedonism to the point that a chaos god (Slaanesh) was born in the immaterium. This event created the eye of terror, a huge warp rift, which is a place where the real universe and the immaterium blend together
Basically, the highly psychic eldar empire became completely consumed by hedonism to the point that a chaos god (Slaanesh) was born in the immaterium. This event created the eye of terror, a huge warp rift, which is a place where the real universe and the immaterium blend together