Horn of beckoning death

The horn of beckoning death was a powerful magic item created by the lich Szass Tam, Zulkir of Necromancy and the Regent of Thay, to invoke a spell of necromancy known as the Beckoning Death in order to turn mass numbers of people into his undead servants.

Description
It took the form of a curved horn, similar to a small dragon's horn. It had an uneven mouth at the wide end, a cap or nozzle at the point, and was engraved and bound in metal, as if fashioned into a drinking horn. When held, it glowed from within from an infernal red light.

Powers
The horn of beckoning death required attunement and its powers could only be commanded by a mage, whether a wizard, a sorcerer, or a warlock. When they held the horn and chanted arcane phrases over it, they could invoke the Beckoning Death. It was a spell that was unspeakably unholy and described as "the greatest evil the world has ever known."

When raised aloft, the horn would cause storms to gather overhead and draw down from the sky strange crimson strands that appeared much like fresh blood before turning dark. These would channel through the mouth of the horn, which would then spew red smoke from its point. Initially, the smoke filled an area of up to in radius from the horn. It remained stationary, but expanded by another every several seconds. In this way, the spell could affect vast numbers of people, even the populations of whole cities.

This smoke consumed the souls of all those who beheld it, instantly killing those caught within the cloud and swiftly transforming them into undead creatures under the control of the horn's creator, Szass Tam. Humanoids were raised as zombies. Only living creatures who were not especially resilient were affected, and even the horn's user was at risk if not already an undead creature like a lich.

The Beckoning Death lasted for ten minutes or until the user ceased concentration on the horn. After it was used, it could not be used again until a whole year had passed.

A Curious Precursor
While the Harpers were distracted with the Harpstar Wars in the late 12 and early 13 centuries DR, the corrupt and ambitious Harper Rundorl Moonsklan happened to meet Szass Tam, a Red Wizard of Thay, who was by then the already a lich and the Zulkir of Necromancy. With Rundorl desiring to be 'a Harper King' and the power behind every throne in the North and Szass scheming to destroy his rivals in Thay, the two made a dark deal: Szass would funnel Rundorl information on his rivals and Rundorl would gain prestige by sending Harpers to win victories over them.

To justify this focus on Thay, a land previously neglected by the Harpers, Rundorl spread the story of "the spell of Undeath". According to information he'd 'discovered', the Red Wizards were developing a new spell capable of instantly turning the populations of whole cities into undead slaves in order to quickly produce armies and threaten and enslave all of Faerûn. According to Rundorl, the Red Wizards were yet to perfect a way of protecting themselves from "the spell of Undeath", especially when cast by a rival, and experiments were naturally difficult to conduct. The only things stopping them were these issues—and the Harpers.

The plan went perfectly and Rundorl sent his fellows into battle against those Red Wizards and even zulkirs whom he claimed had involvement in "the spell of Undeath" and both he and Tam advanced in power. Eventually, though, Rundorl realized more Harpers were dying than Thayans and his exhausted men were being assassinated and reanimated as undead themselves, and he rightly suspected that Tam had betrayed him. He broke off the alliance, then got into worse troubles.

And Szass Tam would go on to do exactly what the Harpers had feared...

Szass's Surprise
As Xenk Yendar would recall, when he was a boy in the mid-1370s DR, Szass Tam called all the other zulkirs and all the people of the Thaymount tharch, Xenk and his parents among them, to a grand celebration atop the Citadel on the eve of the summer solstice. A few of the common people carried sun symbols. But it was all a lie—instead, Szass interrupted Zulkir Dmitra Flass as she addressed the crowd and produced the horn of beckoning death from under his robes. With it, he invoked the Beckoning Death, thereby creating an army of undead under his control for his following conquest of Thay. All who tried to flee were slain by Red Wizards in his service, such as Sofina. Xenk saw a girl his age, Ishira, standing alone and lost in the panic and saw parents attack their children. In their fear, Xenk's own parents tried to force their son into the ritual, but he refused and fled, but the mark of Szass Tam on his head glowed with a magical connection. He escaped, but only barely, losing a part of himself to the Beckoning Death and left changed by the necromantic magic. From then on, he would age slowly.

Meanwhile, these undead would doubtless form the basis of the Dread Legions that Tam maintained for the defense of Thay in the 15 century DR.

At some point, however, the Harpers seem to have acquired or stolen the horn of beckoning death, perhaps preventing Tam from inbvoking the spell again. They stored it within the vault of Korinn's Keep, far from the lich's reach.

The Greatest Evil Unleashed
In the mid-1490s DR, the Red Wizard Sofina, now operating in disguise, hired the ex-Harper turned thief Edgin Darvis and his band of thieves, Holga Kilgore, Simon Aumar, and Forge Fitzwilliam, to aid her in infiltrating Korinn's Keep to steal its treasures. But the horn of beckoning death was her true goal and Sofina and Forge betrayed Edgin and Holga and escaped with their prizes.

Two years later, Sofina had aided Forge to become Lord of Neverwinter. But their scheme was far larger and more terrible in scope than simply ruling. One of the Forge's main acts was to revive the High Sun Games, a monster-filled bloodsport that had been banned by Lord Neverember as he considered them too brutal. Forge also ordered the construction of the Neverwinter arena to host the Games. The first Games were to be held in the late 1490s DR, allegedly as a way of bringing the city together, as well as many wealthy visitors from outside Neverwinter, with their riches.

During the High Sun Games themselves, Forge Fitzwilliam encouraged everyone in the audience to stay until the very end, promising "a wonderful gift" for each of them, and later tried to flee the city with the riches he'd stolen. Finally, the culmination of the games, Sofina revealed herself as a Red Wizard of Thay and used the horn of beckoning death above the Neverwinter arena. The crimson smoke engulfed the viewing platform used by the gamblers and the servants, turning Din Caldwell and Porb Piiradost and the others into ravening zombies. Fortunately, Edgin and his thieves used a portal from the hither-thither staff to pour the stolen treasure from a hot air balloon over the stands and streets, leading all the people out. The Beckoning Death was rendered useless and Sofina's concentration was broken, ending the spell.