Masque of the Winter Sun
The Masque of the Winter Sun is a Harlequin Company and is one of the smallest Harlequin groups that guard the Webway. They were most recently seen fighting alongside the forces of the Craftworld Mymeara and Alaitoc during the Betalis Campaign on Betalis III. In that conflict their holo-suits made them virtually invisible in the never-ending blizzards that dominate the Tormus Delta, enabling them to quickly bypass the Imperial's defense lines. Only the intervention of the Great Company of the Wolf Lord Bran Redmaw saved the Imperial Guard stationed there from certain death.
Unlike other Masques, the Harlequins of the Winter Sun have not performed for, or fought with, the Dark Eldar for many millennia. The reason why is unclear, but their signature dance, the Broken Chalice, is a tale of treachery and hints at an ancient slight by their dark cousins.