The Eldar

The eldar are an ancient race brought low by their own actions. Nearly wiped out by a cataclysm that birthed the Chaos God Slaanesh, the entire existence of the Craftworld eldar is now based around avoiding the attentions of that predatory power, which they know as She Who Thirsts. Following a rigid system of Paths that keep them focused and prevent temptation from striking, the eldar are masters of their chosen arts of war, coming together in battle to form a symphony of death against which none can stand.

Read it because
The eldar are the most capricious and fickle of all the races of the Imperium, attacking without cause or warning. These tales are an invaluable look into the various cultures of the eldar, exposing their customs and their ever-changing motives.