We've been playing a big tourney this weekend in Bilbao and more than one player asked this same question.
Nature's Revenge
Rarity: R3
Permanent-event
Playable on a site in a Wilderness that normally is a Border-hold or a Shadow-hold, or on a non-protected Wizardhaven in a Wilderness . All versions of the site become Ruins & Lairs and each gains an additional automatic- attack: animals Ñ each character faces 1 strike with 7 prowess. Discard this card when the site is discarded or returned to its location deck.
I found this on CoE 11:
19. Nature's Revenge is on a Hidden Haven'd site. Is the new auto attack cancelled by HH?
*** As I understand it, a wizard haven is pretty much like a haven for being a site type thus, when Nature's Revenge turns it into a Ruins and Lairs, it is no longer a wizard haven eventhough the Hidden Haven card isn't discarded yet. If the new auto attack was cancelled, half of Nature's Revenge would be moot. I'd say that hidden haven doesn't cancel the new auto created by Nature's Revenge. I mean, was Isenguard able to cancel the ent attack? Uh... nope.
This one is from a newer digest:
Nature's Revenge says, among other things, that it creates an
auto-attack at an unprotected Wizardhaven. But since Wizardhavens all
have the language on them that "all attacks against companies at this
site are cancelled", what does Nature's Revenge do?
*** Nature's Revenge overrides the text on the wizardhavens.
If it's played on an unprotected wizardhaven, I don't see why it shouldn't override wizardhaven texts (?) As Mikko says, NR wouldn't make much sense otherwise...