This is a unit in the computer game Dominions 4, specifically the Late Age nation of Bogarus, which combines elements of medieval Russia. From the Dominions 4 manual [PDF] 118:

The cultural origins of Russia aren't something you'd expect to be addressed in a fantasy strategy game. The fact that you can find a synthesis of mythology and anthropology derived from a longrunning historical controversy in the nation backgrounds for Dominions 4 demonstrates just how far from elves and orcs an erudite game designer can travel in creating a compelling, fascinating milieu. And still populate it with fireballs and broadswords.

The genesis of the first Russian state and its culture have long been a tendentious point in Russian historiography. Known as Kievan Rus and centered on that city before the rise of Muscovy half a millenium later, its origins have been fiercely debated by Russian, Scandinavian, and western European historians, none of whom know what a dominion spread check is. Proponents of the "Norman theory" emphasize the references to Varangians, or Vikings, in The Primary Chronicle, an Old Church Slavonic text compiled in the 12th century and a key source for understanding the history of the Eastern Slavs.

It then goes on to cite Nicholas V. Riasanovsky's A History of Russia, which includes an English translation. It's fairly common for these "re-imaginings" to combine different historical elements, for example:

I ran a quick search on some names and all I found was a 'heretical' Christian offshoot from Russian , that whilst it was claimed that they were flagelents there is no proof.

The Khlysty were a Russian Christian sect that was rumored to be flagellants (an occasional practice that has cropped up periodically in various incarnations of Christianity). As an underground and persecuted sect, the details of what they actually believed and did are sometimes hidden by libel and secrecy - but flagellation pops up occasionally in Christianity, and tends to have a negative connotation. For example, see the albino with the cilice in Dan Brown's The Da Vinci Code.

The creation of wings seems similar to the practice of removing the lungs of the dead out their back to make wings seems similar (sorry I can't name this practice).

The "Blood Eagle" was an infamous form of execution/body mutilation attributed to Scandinavian peoples, although there's a strong argument that it could be the result of misinterpretation and mistranslation; Roberta Frank looks at the question in depth in Viking atrocity and Skaldic verse: The Rite of the Blood-Eagle [PDF].

So the Dominions 4 developers took different historical/quasi-historical elements and combined them together - with a healthy does of Clive Barker-style body modification/horror, as featured heavily in the Hellraiser movies based on his works.