Am I reading it right? Isn't it impossible, or extremely difficult, to prevent an opponent from shutting the post's ability down with Orc development destruction? For example, if my opponent has a deveolpment in play, and I sacrifice my Stunty Smasha to destroy it, can't he just sacrifice the development in response to blank out the post? And even if I clear his captial of all developments, can't he just play a development before his next battlefeild phase and sacrfice it to negate the post in response to any action I take to get rid of it?

I think you really do need to play Dark Elf discard abilities that aren't restricted to your turn (Caught The Scent) or the Battlefield phase (scout ability) so you can knock out an opponent's hand before his capital phase to prevent his play of a development.

Even if it doesn't prevent attacks completely it is still a great card. It will be a stumbilg block for Dwarf development themed decks and any empire running venerna . I see it like Phoenix Ward even if I'm not going to totally prevent you from attacking a zone, I will definitley discourage it.

Of course you can always sacrifice a development in response to any action targeting your dev (except against Grimgor because it's a Forced effect). This is because the Action says : "sacrifice a dev TO…" so it is the cost of the action and the dev will instantly go to your discard pile.

But considering that Orcs are good at removing devs and you can only play one dev per turn (usually), it'll be hard to blank many Warning posts.

In the case of Grimgor, you can sacrifice the Dev in response of the action that put into play Grimgor.
You musn't wait the trigger of the forced effect.

That's right, Juzam. Thank you

You can even sacrifice development in response to Grimgor being played from hand.

Agree with Ellyrik.

Also, given the ambush mechanic of the Eternal War Cycle, ever development counts and this support is a real pain in the *** for any deck that rely on ambush / not drawing enough cards per turn (i.e. rushing you).

Warning post is also not a unique card and if u have two in the same zone, an opponent could actually run out of developments (1 dev per turn, 2 dev required to hit 1 zone) and can only attack you once every two turn (or even less if you utilise orc development destruction deck).

A great card for orcs imo.