I think there is a strong argument to be made that only Jem'Hadar already in play should be able to be placed on
Jem'Hadar Shrouding, AND that there should be minimum number of Jem'Hadar required to be moved off of Shrouding to initiate an away team battle (I personally would go with 3 if only one Jem'Hadar can be placed on Shrouding per turn, 6 if two can be, OR with a number equal to the size of opponent's away team on planet.)
As currently written, this card works as an additional free-play engine for the Dominion and still would even if you limited it to one card being placed there per turn from hand per turn.
First, it doesn't actually call the Jem'Hadar you place on it "reports" or "free." Instead, it's one of those weird cards like
Crell Moset that allows a whole bunch of additional reports without actually calling them, "free", and so would not be subject to any limitation on playing cards for free. In other words, if you bring this card back, I can throw a bunch of Jem'Hadar into my
Guess Who's Coming to Dinner deck and run them to harass my opponent despite the limit on free reporting being limited to Qo'nos. (I also imagine that a BUNCH of cards CC will issue in the future will have limitations of "no free reporting", given that there's clearly an effort to block free report stacking in this manner using recent cards like
Staging Ground and
Guess Who's Coming to Dinner.)
Second, it also evades the limitation on reporting only one Jem'Hadar per turn contained in
Reward from the Founders. True, you would be limited to playing and battling with two Jem'Hadar at a time if you go this route, but you could likely initiate a battle with two Jem'Hadar, stop your opponent's away team, one of your guys probably dies, then you can still beam one up to your ship on your next turn or play a
hidden fighter. Still a pretty good deal: you got an extra personnel, your opponent ws blocked from doing anything for a turn.
Only allowing Jem'Hadar to relocate to Shrouding would also prevent using this as a substitute for rogue borg, since you actually would need a reporting location for the Jem'Hadar (and likely a free one). Requiring a minimum number of Jem'Hadar to relocate would also prevent just harassing an opponent every turn. Locking an opponent out of a planet mission would require
Post Garrison (which you could download using Taking Charge if you had First among the Jem'Hadar you play to that mission from Shroduding), not just placing one Jem'Hadar on Shrouding and a new copy of Shrouding every turn.
These limits hardly makes the card useless. I think you could make a kick-ass dominion deck that entirely avoids using a wormhole by using
Internment Camp 371 as you reporting location, many multiples of
Amar'itak and the old
Deyos, young Jem'Hadar and birthing Chamber combo, along with several
hidden fighters and
Establish Dominion Foothold or
Construct Starship. You can could relocate a bunch of Jem'Hadar the first time an opponent tries a planet mission, play hidden fighter and then download a
Remote Supply depot in the opponent's quadrant. Not too shabby, if you ask me.