thanvannispen's "whisper5", edited to remove some staccato whispers, make it suitable for looping, remove/fade out the last few whispers, and remove unused right channel (i.e. make mono). Also …
mike campbell's "F.S. 7 demon growling", slowed to 40% speed and enveloped with Audacity to make the volume a bit more level. Doesn't have the bass you'd think …