An exile of Myth Drannor, the half-elf mage Vhyridaan the Mad was self-taught in the ways of High Magic. He tried to store his knowledge in a kiira, but failed—the stone absorbed not only his knowledge but his body and soul completely, as well as the one magic item he had with him, a ring of spell turning. His soul remained trapped inside the stone thereafter.
The mantle stone eventually came into the possession of Laummas, the Lich-King of Hlondath. Laummas fell in the battle of Twilight's Falling in 712 DR, part of the Weeping War against Myth Drannor. It was snatched up by his minion, the treacherous Nezras, who had it but briefly before giving it up to Aulmpiter, the nycaloth commander of the Army of Darkness.
The mantle stone remained with Aulmpiter until the Fall of Myth Drannor in 714 DR. There, in the Bane's Duel, Aulmpiter dueled Captain Fflar Starbrow Melruth to the death. In a desperate tactic, Fflar tracked the motions of the mantle stone and, near the end of the fight, he swung his sword Keryvian to intercept it, appearing to shatter it in a single hit. After the explosion that later annihilated both combatants, no trace of the mantle stone was to be found.[note 1]
The mantle stone of Vhyridaan functioned in all respects like an ioun stone. Specifically, it worked similarly to a vibrant-purple prism ioun stone: once a day, it could be used to store spells like a ring of spell storing. If the gem was clutched tightly in the hand or pressed to one's brow, the owner could will three memorized spells or similar powers into it. However, if the spells could be cast at some distance, the soul of Vhyridaan could cast these spells himself when he liked.
Furthermore, if the stone hovered over an owner's spellbook as they studied and memorized their spells, then Vhyridaan could memorize up to three of these spells as well. However, he would almost certainly learn the same spells as the owner.
In addition, thrice a day, the bearer could utter a command word and the stone would protect them from spells, or even turn them back on their caster, similar to the spell turning spell. Previously, the effect was a constant spell mantle similar to a ring of spell turning that only reflected five spells each day. This power would renew after eight hours' rest or twenty fours without rest.
Bearing the soul of Vhyridaan, the mantle stone was a sentient item. He could communicate mind-to-mind when in contact with the stone's owner. He had no ego and no power to possess the owner. Thanks to this sentience, the stone actively avoided efforts to grab or attack it.