The Eye of the Abyss is a Gem of great power.
Twitch Keenear used the Eye of the Abyss gem and summoned the Demon Anag'rha'su, Lord of the Sixth Circle from the depths of the Abyss.
Anag'rha'su sent Twitch on a quest to the Halpi Mountains to gather a pair of dwarfish gauntlets, which would allow Twitch to unlock the full power of the Eye of the Abyss gem, and in turn will grant Twitches Brood Mother the most powerful Ratkin nest.
The eye was eventually obtained by Artakl the Ghekkotah Clutch Warden, Magnilde the Varangur Demon Hunter, Eckter the Placoderm Defender and Jarvis the Ophidian-Obsessed Mage during the Dungeon Saga: Eye of the Abyss campaign
which was lost by Magnilde of the Fallen into the boiling depths of the Fourth Circle during the Edge of the Abyss. Its destruction rippled through the Abyss like a beacon call to all its foul denizens, screaming for revenge.
Afterwards, Korgaan the God of the Air, showered Magnilde with gifts and praise.