This sound is from Bonesinger - Warhammer 40k Soundboard

A Bonesinger serves as a psychic engineer and craftsman for the Craftworld Aeldari, the Asuryani. The Bonesingers are the builders and maintainers of all Aeldari weapons, tools and even the Craftworlds themselves. These powerful xenos psykers are gifted in the arts of construction using the solidified power of the Warp. They use their telepathic ability to summon or psychically generate the solidified substance of the Immaterium the Aeldari call Wraithbone, which they construct into buildings or tools and use to repair the Aeldari's vehicles, weapons and armour.