1 minute ago, Sherizaahd said:I agree with this, I think the point of this ability is to add trays, rather than just to regenerate trays which have been removed. I also think that it's reasonable to expect him to be able to add units however you please, since the rule for having legal unit layouts is for army building. Indeed there is a line in the rule book which specifically addresses that units will change throughout play into illegal configurations, which in no way invalidates them during play.
RRG pg 3, Army Configuration During Play sidebar.
During a game, players do not need to continually check if their army is legal. As players lose figures, trays, and upgrades, their armies may become configured in ways that are counter to the army-building rules. This is okay— the army-building rules only apply when building an army, not while playing the game.
Now, none of that means they won't restrict it to either or both of the restrictions people have mentioned, but I don't see a reason in the RAW that makes any restrictions beyond the unit being Waiqar infantry clearly intended. Hopefully, if they have those restrictions in mind they will add the text to the ability on the card so it's clear from the time the card is in our cold and clammy skeletonized hands.
The problem with adding units in a free-form manner is how quickly you can ramp up threat. A 4x4 block of Reanimates could be boosted to 8 threat in a single round (Violent Forces and a max unstable rune result).