This sound is from Chaos Lord: Warhammer Soundboard

A Chaos Lord is one of the most powerful of the Champions of Chaos who often serves as the commander of a Chaos Space Marine warband and the other Forces of Chaos. A Chaos Lord is usually, though not always, a Heretic Astartes himself. They are not necessarily those who rose through the ranks properly in a hierarchical fashion, but are often those most blessed by the Chaos Gods or simply the most powerful or charismatic individuals among the Forces of Chaos.