Education block: cannot spend more xps to academic abilities. Loses 1 xp /year from the current abilities.
Social block: cannot spend anymore xps to social abilities. Loses 1 xp /year from the current abilities.
Deficiency in Me, Im or Ig (like Bjornaer).
Only can eat raw things.
Deleterious circumstances - casting in cities.
Leaves grow from his body instead of hair.
Became incredible hairy.
Animals like him/her too much - similar like St. Francis.
Back on the Virtue side of things, one could add a similar virtue to Animal Ken, except that the magus is somehow able to commune with plants.
Another Mystery Virtue might be an Nature-based Empowerment mystery where the magus is able to use the life force of a plant to empower a spell or device (maybe that would be two different Virtues) in such a fashion that as long as the plant lives the spell/effect continues. The size of the plant (or collection of plants) being governing the magnitude of the effect.
So, for example, such a magus could use a particular circle oak tree to empower a Creo Herbam effect that created a small bridge. If the oak is ever cut down/stuck by lightning/whatever the bridge falls apart and disappears. Similarly, there could be a meadow where the magus has a Creo Mentem effect in place that creates a peaceful and friendly feeling (Poppies!) while the flowers are alive. In either caase, no vis would be needed.
Regular or long-term enchantment could eventually create a Magic aura.
-K!
Nice idea. It strikes me as a twist on the Verditius Mystery of Binding Animals to devices or to one's Gift. I suggest you have a look at that mystery in HOH:MC and perhaps simply change it from magical creatures to magical plants.
Instead of binding into devices (per se) your new mystery could, as you say above, be matter of drawing out the life force of the plant/tree/etc to power a spell. As with the Verditius mystery, the magus could alternatively bind some power or aspect of the plant to his/her Gift (bark skin on command anyone?) lol.
Call the Mystery The Rite of Harvesting (or some such).
Just don't let any fairies see you doing this 
The Pagan flaw might be appropriate.
You might consider necessary condition: animal sacrifice. The bigger the animal, the larger the effect.
Thank you all, some very nice suggestions (but keep 'em coming anyway, one can hardly ever get enough of inspiration).
I'll be sure to write back here once I write things down.
Nature Magus
yes, it is simply another version of Elementalist, but which 4 Forms to include...Animal and Herbam are no brainers, but the other two have several good pros and cons. Auram is one I like, because the weather is IMHO an important part of Nature. The sunlight is not controlled by controlling the light itself, rather than making sure there are no clouds. Terram or Aquam...Nature is not truly metals and gems, but earth and stone, again this it not living. Aquam covers the lakes and streams of nature, but not anything else, like the poisons and all other unnatural , produced or refined liquids. I might go for just An, Au and He - and then jazz it up to 2 exp instead of just 1.
Special Durations etc
I also like the idea of making some new Durations, like some of the special R/D/T for Faerie magic. Something tied to natural occurences, the life of trees and animals, migration of birds, hibernation of a bear, untill the hottest or coldest day...something like that. It needs some serious work though.
Versions of Verditius Mysteries
I'll make sure I look into Verditius again, so see if I can bodge a Nature Myster based on some of this. At this time, I can't recall that specific Verditius Mysteri mentioned.
There were also some good ideas for Flaws, to use as ordeals for initiation into various Mysteries, sacrificing some city-skills or very academic stuff. I might add some minor mystery to initiate Cyclic Magic (Positive), it seems very appropriate for Nature Magi, perhaps with some additio to the regular version.
I just had an idea, to a Nature Mystery, where the magus gains the abiloity to use Natural rather than Astrological resonance for use in Ceremonial casting, using Nature Lore rather than Artes Liberales/Philosophiae.
ROFLMAO!
The Magus "It"ianus? lol
hmm, how about the following special Durations:
Moon/Season/Climate:
Season: The spell lasts until the end of the last day of the season (obviously) Spells with this duration must be rituals.
Climate: spells with this Duration may only be cast on climatic conditions of a given target area. Most often associated with Muto or Rego effects.
I'm also thinking that your wilding magic might require some form of totem (spell focus) in order to effect Target areas larger than individual. A sort of representative type (plant from a particular field, tree limb or stick from a forest glade, animal part/piece of fur from a particular local species or herd) etc.
The specific Verditius Mystery was the Greater House Mystery: Bind Magical Creatures (pg 134, HoH:MC).
Nice idea. Another reason why I personally see Te as part of nature. You could base such resonance off the concept of Ley Lines (magnetic currents under the soil) and call it "Gaia's Veins"
Nature Lore sounds academic, too. I suggest use rather Survival or Wilderness sense.
Another virtue/flaw pair:
1st step
Study bonus and -3 from learning books.
2nd step
Learning from the world.
Look at the study bonus table and take the circumstances as being summas with quality 10.
Its flaw part is he gets -6 from learnig books.
That's Vim.
Good counter argument! Upon reflection, I do agree with you. 
"A flower by any other name..."
Does Nature Lore sound too academic? It's just like the other Mystery Cult's [House] Lore.
I need the Nature Magi, as a Mystery Cult, to have a single, exclusive Ability regarding their mysteries. All other Mystery Cults have this. So not an Ability readily available by others, or from Supernatural Ability Virtues. Call it "Mandalus Lore" after the name of the newly seperated house, or "Merinita Lore" to refer to the original master and founder. Nature-, Wilderness- etc. The Right Name is bound to occur to me at some point.
Can any one remeber the names of all other Mysery Cult's [House/Mystery] Lore abilities? Of course, I'll look it uo in my book when I get home...but I need to see if there is some coherent way of naming them.
Or make it the other way round: Season is equal to year duration but not a ritual. I think this was used in some other mystery but I do not recall which one (Serf's parma)
Other durations may include:
until natural condition ends (like: as long as the westwind blows) would equal sun duration
until natural condition starts (like: when the next snow falls) would eual year duration
I tried to avoid "until" Durations since these already belong to Fairy magic.
My thought on "Season" was that it should be more rightly comparable to Moon since it falls between that and Year but is closer to the former in length. Since it is of longer duration than Moon, it would seem proper to make it (like it's Year counterpart) a ritual Duration.
Besides, as I see it, wildling magic would quite likely be more ritual based anyways, hearkening back to pre-Hermetic traditions of natural magic evocation more so than the formulaic processes of Bonisagus.
I get you already.
BoXer:
I'm a skilled orator you know. 
Watch out, Cicero! lol
Flaw: Necessary condition: In wild area/outside settlements
Virtue: Make it like Magical Focus.
I like the option of 'Ways of the Land'.
Don't limit it to Forms...
Fire is part of Nature
Auram is part of nature
Aquam is part of nature
etc.
Instead concentrate on what the magic is doing. When you cast a spell on a tree (say), you can double your lowest art. If you cast a spell on a person, no bonus. If you cast a spell on a river..yes. Rock..yes.
Armor..No, House...No, horse...yes.
etc
So the Mystery cult would look like this..
Minor Mysteries:
Affinity: Choice
Study Bonus
Puissant...
Skills- Survival, Animal lore (affinity), Plant lore (affinity)
Major Mysteries
Ways of the Land
Nature Magus (Focus)
My Rooks worth
I can see that. But I don't think that Faerie Magic and Nature Magic needs to radically different. Another way to look at it is that the Fae LIKED House Merinita for a reason. Folks were anthropomorphizing Nature and turning a good part of it Fae.
These mysteries just get you back to the real roots of it. 
-K!
They AREN'T "radically" different, not in spirit anyways, but if we're in the process of helping someone create a new mystery cult, why not develop some novel approaches rather than taking what is already developed for another realm of magic?
Seems to me most of our suggestions are borrowings or derivations anyways, so in this case I thought a Duration (or Durations) wholly its own might be in order.
Sue me for trying to be clever
You'll hear from my attorney shortly!
Seriously though, I agree. Novel ideas are good. I guess I was trying to point out that they don't have to be and it would still be just fine.
So, let's put it to the crowd: What mystery did Quendalyn's (sp?) rival know that he was unable to pass on? What secret(s) did Q quash? And is there an Ex Misc or Bjornear bunch that rediscovered them or maintained them in parallel?
-K!
I see Bjornaer have a sub-tradition of some nature-related mysteries, from refugees from Merinita when Quendalon went the faerie way.
Hermetic Theurgy and such, is mentioned, but just refers to The Mysteries. Can someone explain what these are about. I need to know whwther to buy The Mysteries right now, and wait with City & Guild, or which way my priorities lie.
Unless your running a story more for the grogs the Mysteries will be much more useful.
review of mysteries here and first look thread here