Containing the bound essence of innumerable Slaanesh followers who died in blissful slaughter, the air around the Rapturous Standard is filled with their ecstatic howls and the overpowering waves of heady, exotic musk. Any unit with a model within 6" of the standard is rendered immune to fear by the overwhelming waves of sensation radiating from it and will pass all Morale checks they are required to take automatically.
Rapturous Standard
Source: Codex: Chaos Space Marines (1999), p. 29