I modified the Pretorian Stalkers' reference card to fit in with the new Dark Legion ELITE FORCES Reference Card (which I am also uploading here as a separate file).

At the time of this upload I plan to follow this rule: If three or more corporations begin a mission at Rank 5-6, OR if one is at Rank 5 and a second one is at Rank 6, then use the ELITE FORCES Dark Legion Rank. Remember that the Pretorian Stalkers come as a pair. :)

This should make these enemies even more deadly and a bit harder to eliminate. If the Doomtroopers are still having a relatively easy time of it, then throw in the Pretorian Stalkers' Force Card occasionally to beef up a mission -- maybe have two of them chasing the Doomtroopers instead of the Ezoghoul in the Trapped! mission. The Pretorian Stalkers' Force Card can be found in the Brotherhood Expansion pdf file.

Note: It seems that the download method here is to right click on the link above and choose the "Save Target As" option, OR, if you click on the link then right click on the picture and use the "Save Picture As" option. :)