The Silent Thunder

The Silent Thunder was a spell used as a weapon of war against the town of Arginbury by the Wardens of the Central Plains, a short lived alliance between the rulers of Klaractazum and Zalgurim during the Time of Terrors, which sought to gain control over the ancient heartlands of Myruthea in some kind of peculiar and brief echo of the struggles that had characterised the Myruthean Unification Wars many centuries before.
Working with the war mage, Herakaldyn Bell, the cousins (and leaders of the alliance) Jera Ward and Talkon Ward combined their powers to research and craft an arcane resonating spell designed to produce sound waves capable of obliterating stone, metal, and flesh.
Herakaldyn Bell at the head of the first army of the Wardens of the Central Plains was changed by the leaders of the alliance with the conquest of Arginbury. The town had refused to join their alliance peacefully and had offered sanctuary to some important political exiles who had fled from the Wardens. Arginbury continued to defy the army that lay seige to it, even when threatened with a terrible reckoning if its leaders did not surrender.
On 16th Kerax 3376 APC the war mage triggered the spell herself to unleash its fury on the stronghold of independence. But something terrible went wrong. Instead of controlled waves, the spell generated a massive, soundless pulse, a “Silent Thunder,” that radiated out in all directions from the point of invocation rather than being focused up the valley as intended. The deadly pulse was entirely soundless yet devastatingly powerful, killing everything within a wide area. Ironically, Arginbury suffered much less than its attackers, protected by the geometry of the surrounding mountains.
The Silent Thunder killed Herakaldyn Bell immediately and had such a severe effect on the invading army that it resulted in the collapse of the alliance of the Wardens of the Central Plains and weakened both Klaractazum and Zalgurim for a generation, creating a deep fear of sound-based spells and an aversion to that particular line of acoustic arcane research which remains to this day.

Effect

The spell was intended to produce a focused funnel of intense sympathetically resonating sound, powerful enough to disintegrate any enemies in its path, demolishing buildings, destroying vehicles and killing any living thing within range of the zone of fatal transmission.

Side/Secondary Effects

Instead of controlled waves, the one and only time the spell was used, it generated a massive, soundless pulse, a “Silent Thunder,” that radiated out in all directions from the point of invocation. This issue saw the users of the spell more badly afflicted than the intended target.
Where the Silent Thunder struck buildings crumbled in an instant, bodies collapsed without a mark, and fires sparked spontaneously, feeding on the sudden vacuum of air. Survivors experienced a strange ringing in their ears and found their voices silenced—rendered mute by the impact on their minds. This left them with only fragments of memory, as though the event erased part of their consciousness.

Discovery

The spell was crafted by three mages working together under the banner of the Wardens of the Central Plains, namely the leaders of the cities of Klaractazum and Zalgurim, the cousins, Talkon Ward and Jera Ward and the war mage who was the general of their first army, Herakaldyn Bell.

Herakaldyn Bell by DMFW with Night Cafe

Jera Ward in Zalgurim by DMFW with Leonardo AI

Talkon Ward in Klaractazum by DMFW with Leonardo AI