[SpyroD]

Premise: I'm a collaborative GM, one who ask players often, one who prepare a good chunk of adventure with the players and my players are some types who like investigative, mysterious, researching games mixed with a dose or two of action. A thing I consent my players to do is, once in a time, give something they want as reward or found it in the game and take it until they endure. One of them asked me a thing more strange that usual: his PC is a mage and want some sort of "magic object" who he could bond like a focus, the object have only one property, he (once bound to it) could see the astral where the object is even if the object is out the line of sight.

I don't know if a thing like this exist in canon but after the artifact rush I see is not entirely out of possibility in the current canon (as far as we know it).
My problem is help me to design and stat it in some useful terms. I don't want an object excessively poweful at that... well in the end I'm asking to design a possibile artifact, some one want to help me?

[Mal-2]

I don't know what you might want for rules, but it should look like this (from http://boingboing.net/2012/09/19/eyeball-creep-a-very-special.html)

[SpyroD]

For the spirit of Big D! Holy drek in a hole

On a serious side I want help rulewise and for what exactly I could put inside as power, or is better going in home ruling?

[Mithlas]

Sounds like something of an astral "bug", and presumably it might operate on a similar principle to the Clairvoyance or Clairaudience spell. Once bonded, when activated the mage could view astrally as if present at the location of the bonded object, at least within the limits of what those spells might yield. That's what it seems like you are looking for.

[Mal-2]

Okay, a few thoughts off the top of my head.

Once bonded, the object acts as an extension of the characters own aura, with a link passing from reality at the object's location, into the astral, through the metaplanes, and back to reality at the mage's location.  A few possible uses for this odd behavior:

Allow the object to act as a 'spotter' for ritual magic.  Drop it in place ahead of time, and you don't need someone to go out and anchor the ritual for you.

Allow the mage to take a metaplanar shortcut from his current location to the location of the artifact while astrally projecting, without requiring a metaplanar quest.

Allow the mage to cast spells originating from the artifact, no matter whether he has line of sight to it or not.

Allow the mage to see through the artifact's eyes in either the physical world, the astral, or both.  This could be an extention of the previous ability if you require him to cast Clairvoyance first, or just a special perk for having an aura in two places at once.

Allow the Horror known as Aazhavat Many-Eyes to target the bonded mage with his Corrupt Reality power. (Earthdawn Horrors, pg 12-15)

[Mirikon]

Allow the Horror known as Aazhavat Many-Eyes to target the bonded mage with his Corrupt Reality power. (Earthdawn Horrors, pg 12-15)

NO! No, no. Nononononononononononono! You do NOT want Aazhavat showing up in your campaign. If he is here, that means all the other nasties are already here as well, and we have the runup to the Apocalypse. It is TOO SOON, barring major developments in Azzieland.

[Mal-2]

Oh, it's not here.  It's just that that link through the metaplanes goes way, way deeper into the metaplanes than it appears at first glance. 

Besides, the player is literally asking for it (whether they realize it or not).

[Mirikon]

The only, and I do mean ONLY, way this works without the Apocalypse coming is if there was some artifact of his left behind that hadn't gotten found by the Foundations, the Azzies, the IEs, and the Dragons. Especially since IEs and Dragons have major roles in the Foundations, if that artifact was found by anyone other than the Azzies, or someone who went diving in an alchera, then it has been destroyed by now. If the Azzies found it, it would be locked up someplace, and kept 'just in case'. And if even the slightest word got out to the IEs or dragons that there was a Horror artifact at large in the world, they would spare no expense in finding and purging it.

Do NOT go down that road. End of the world is never as fun as it seems on the TV.

[SpyroD]

The end of the world comes without salvation ticket attached 

In everycases is possible without invoking the horror thing?

[Mal-2]

In everycases is possible without invoking the horror thing?

Sure.  I was (mostly) kidding about the horror thing.