I've been trying to determine what the Form noted next to a creatures Might score means for Hermetic magic. In the RAW it says that the listed Form can be used to ward against the creature and in ROP: Divine (pg 21) there is a note that angels can be warded and targeted against by the Form noted next to their Might.
Besides warding, which makes sense, how else can magi use the listed Form against the creature?
I don't believe the specified form is to be used "against" the creature, more for the SG (and to some extent, the players) to understand the relevant magica force behind the creature.
For example, if I have a Fire Elemental, his form is probably Ignem. But as a Fire Elemental, the creature probably has a Greater Immunity to fire, so using Ignem against it is probably as effective as beating a dead horse.
Also, remember that these creature statistics are not written in stone. So if you want to modify them, I use the form as a guideline to what powers a creature may or may not have.
Well, I see what you are saying in the first paragraph but Rego Ignem is the way you can make a fire elemental do anything you want (see Mysteries pg. 28 ). Rego (Form) base 5 to control a disembodied spirit of (Form). So, while I agree that trying to harm the fire elemental with a Pilum of Fire would probably be worthless, the Ignem Form is used to control the creature.
The RAW and ROP: Divine seem to indicate that the Form associated with the creature can be used in some magical ways against it, but only warding is actually described. Additionally, the Rego (Form) base effect from Mysteries seems to allude to more uses of the Form against a creature but it is never clarified.
I sense a subject that will likely be covered in RoP:Magic...
-Ben.(Who eagerly awaits RoP:M)
I definitely hope it is clarified! But, this goes way beyond creatures of the Magical Realm, and concerns creatures of. all Realms which is why I decided to pose the question now instead of waiting until May. sob
For me, I'm most interested in how Rego (Form) can be used. Can a Rego Herbam spell be used to control a creature that is listed as: Might (Herbam)? Can I use the base effect guidelines for (Rego) Animal, Corpus, and Mentem as examples for base effects to control creatures with the Form listed beside their Might?
IMO? Yes. And the base 5 should apply through all forms, yes.
I would let Re(Form) and Pe(Form) effect creatures with that form listed as their form , I would also let such creatures be effected by Vim wards and might sapping spells.
I view the Vim effects as being general effects which work on any (Faerie, Demon, Angel, magic creature) while the form other form spells are more limited by being specific to creatures aligned to their form and the targeted realm meaning they are less ueful in general but can be very useful if you know what you are going to face and are good with a particular form
Totally agreed 
I had the same conclusion based on my reading of the RAW and ROP: D. I hope they clarify this in ROP: M though as I haven't been able to "prove" it to my troupe. I will point them here though 
One thing that's been bothering me is that the "Summon and Command" guidelines in TMRE (page 28, third column) seem to imply, by contrast with Vim, that Re(Form) spells can affect a "spirit" regardless of its realm.
I penalise Vim-based wards where there is a logical alternative form. This reflects my view that Vim is more general purpose but not as efficient in the specifics.
with Vim, you have 4 spells and cover everything, with other forms, you would need 9 spells of differing forms to cover everything, but, Vim is more limited in other regards, it is easy to ward against magical stuff, less easy to do something about non-magical stuff
I'd rather see that as a difference in approach, in one case you'd say "witches are made of wood", so you can ward them with ReHe, in the other you'd say "witches can turn people into newts", so you ward them with ReVi.
In any case, I've seen no real justification for Re(Form) spells to be an exception to the underlying rule that spells must be designed separately for each Realm, nor can I claim that Vim spells' superiority isn't fully justified due to their specific domain of application: power. After all, Flambeau magi do have their Pila, and while I can't read the designers' minds (my Mentem-fu is too weak for their parma), I don't think players need another excuse to turn away from Vim as being only useful in very specific situations.
I'm fully willing to eat my words if someone shows me that Vim Is Best For Everything (and it makes coffee too!)
I don't see that as a problem, myself. It makes Form-specific wards useful, rather than vastly inferior to the Vim equivalents. I see no unbalancing in the idea that an Archmage specialised in Herbam can sit happily in a circle whilst Infernal, Divine and Faerie trees take turns to bounce impotently off his shielding. The form targets, well, the form, whilst Vim targets might.
I tend to regard things like Ward Against Faeries of the Wood to be legacy effects.
Where I do become curious is where to bring in specificity. Does the ReMe spell control Spirits, or does it control Ghosts, Spirits of Emotions, Elementals or Genii Loci? Does I learn "Bind in Shackles the Essence of Spite", or do I learn "Hold Fast to the Spirits of Passions" which gets all emotion spirits?
Yup, either you can target a creature using a Realm specific Vim spell or you can target the creature's Form with the appropriate Form. As with most magical effects there are a number of ways magi can get the job done.