Somewhat anti-climatical, to me, I'm afraid. We -the ''fans'' of the Horus Heresy- have always known of Dark Angel contact with the Night Lords along the Eastern Fringe, and have always anticipated a novel of such; some more eagerly than others. To hear that this will be downgraded to a short-story is interesting in the aspect of ''It shall certainly be written of'' but I surely thought this would be deserving of a full novel? The Dark Angels have not been painted to their full... glory, thus far (Bar that of Thorpe) and the Night Lords, well, I would have enjoyed a 2-parter by both AD-B and Thorpe. Two strong authors of similar talent, if differing styles.
If something as ''big'' (Perhaps a tad hyperbolic) as this is put within a short, I fear that -what I am truly wanting- the Cleansing of Olympia shall also be...
Anyway, in Soul Hunter, were there not several times in which the Covanent of Blood is mentioned ''being at Terra''?