Mirror of Communication (3.5e Equipment)
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This plain-looking mirror can be any size, and can be glass or metal. It has an astounding capacity for communications.
Firstly, it radiates a strong divination aura when viewed with detect magic.
Each mirror has its own unique ID (often the personal rune or royal seal/crest of the one it belongs to), which identifies it from all other such mirrors. In addition, each mirror can hold up to 20 such runes of other people. This creates a sort of "speed dial," especially since a casting of Arcane Mark is needed to add another mirror the the list (or "call'" someone who is not on it). Each mirror has a unique command word used to activate it. This is the same word used to accept incoming "calls."
Each mirror in the "buddy list" can have a six-second sound attached to it when it is added. When a call is incoming, the rune of the calling mirror will appear and the sound (if any) will play. The range of the mirror's communication is effectively unlimited (until space travel is developed), unless it means crossing planar boundaries.
Also, if you use the plane(s) of mirrors in your campaign, then each mirror opens into its "buddy list." Note however, that since two mirrors are likely to have different buddy lists, that you are very likely to enter onto a different plane of mirrors on your way back (and the destination mirror may not even be in this one's list).
Cost: 5,000 gp; Cost to create: 2,500 gp
Prerequisites: Caster Level 9th, Craft Wondrous Item, Clairaudience/Clairvoyance, Read Magic, Arcane Mark
 Greater Version:
The Greater Version is the same as above, except that it can cross planar boundaries and can hold 30 other mirrors in its "buddy list." The cost is doubled, and a Scrying spell is also needed in the crafting process.