ArcanaNet (3.5e Equipment)
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The ArcanaNet is quite obviously based off of the modern-day internet. It requires a special tablet to access, found here: ArcanaNet Tablet.
First off, nobody knows how the ArcanaNet works, or who designed it. However, given the occasional tweaks and modifications, it is quite obvious (to those who use it) that someone still manages it.
The ArcanaNet allows for several different features, described below.
Search for/buy a spell: The ArcanaNet's database holds just about every spell ever made, even many of diety-level power, epic power, and many that have been lost for thousands of years. However, the organization system is confusing, requiring a Knowledge (arcana) check (DC = 15+spell level) to find the spell wanted. It then requires a Spellcraft check or Read Magic spell to interpret it, as normal. It must then be studied, as normal (PH1 179) Once the spell is found and studied, it can be "downloaded" to the tablet's spell selection. Doing so requires that the above conditions are met, the spell is on the tablet's "screen", and then placing one pound (50 gp) of gold on the "screen" per page of the spell. Once this has been done, casting Arcane Mark on the tablet burns up the gold and begins downloading the spell to the tablet. Only one spell can be downloaded at a time, and it takes two hours per level of the spell.
Due to the complex format of the "spell catalog," you must know exactly what spell you are looking for, or the check to find it automatically fails. This effectively prohibits access to epic or diety-level spells unless your character has already discovered them (which defeats the purpose). In addition, your character must have at least seen the spell cast or read of it somewhere to know of its existence. Your DM is well within his/her rights to have you make an additional spellcraft check to know of the spell's existence before you can search for it in the database.
Chat Feature: this is basically just an IM client. It can hold up to 20 friends' "tablet identifiers."
Video Chat: This basically allows the tablet to connect to a Mirror of Communication. It can store 20 "mirror IDs." Not available unless Mirrors of Communication exist in your campaign. Note that it only shows up in a plane of mirrors while a call is active, as it is not a true mirror. However, on the plane of mirrors, a recess is in the wall where the screen shows up, so a successful DC 15 wisdom check (combined with knowledge of the tablet's existence) lets a character know that a tablet docks there while making calls.
Online Gaming: Yes, it's true, now your wizards can become MMO addicts. DM judgement should be used on this, as it can very quickly become annoying when the wizard is busy on MMOs instead of preparing spells for the day (or sleeping). Use of this feature costs 5gp per month, sold in one-month increments.