This image appears with no explanation at the foot of a chapter in the Universitätsbibliothek Karl-Franzens MS 32, f 91v, which was written in Bologna in ca. 1300 (although this image may have been added later). As you can see, it's clearly a portrayal of assuming Kruck to counter Third, a very orthodox I.33 move (pictured on ff 4r, 5r, and 5v of the I.33).

The full manuscript can be had
here.