One option the Daemonhunters are light on are fast attack options. Basically there are none except for grey knights taken as fast attack with a teleport option. As grey knights don't like to associate with radical inquisitors who use daemonhosts this option can also be out. That leaves allies such as Imperial Guard Rough Riders or Sentinels. An allied Witch Hunter Dominion Squad transported on an Immolator seems likely to give a bit more bite than the IG options and fits in with the idea that the Ordo Hereticus might wish to keep a close eye on an Inquisitor that was playing with daemons.