They're referring to two mercenary units: Cylena & The Nyss Hunters and Greygore Boomholwer & Company respectively.
The Nyss Hunters are an extremely versatile unit that are good in both melee & ranged, have decent defensive stats and high
SPD. This makes them very powerful, and a popular choice in a lot of factions that can hire them. They're so popular in fact that the poster was pointing out that a ranking officier (a type of attachment that turns a merc into "Friendly Faction" typically just wind up stapled to the Nyss Hunters.
Then the other poster pointed out that Murdoch (the Cygnar ranking officer) often gets attached to Greygore & Co, this is because he provides a beefy front line unit of the type generally absent & Cygnar and with the ranking officer can be subject to power defensive buffs like "Arcane Shield"