The Great Sigh of Riz Ath

"Power is bestowed to raise up the world." -Riz Ath, First Burgeonend
Conflict continued even after Thánatos "The Destroyer"'s was removed from Potestatem. Hazfen were dunes scorched to glass, great crevasses, and swaths of dead lay across the desert. Riz Ath survived.
Him and his people were the largest group of native Hazfeni to live. A mere remenant of the Perisian Empire's foothold in the great desert. Threatend by Destroyer Breath creations they made The Hourglass. Riz took his trusted council, most powerful soldiers, and greatest scholars to creat the first Burgeonend through Inversion. At the same time the desert rose to this new power with its own threats.
Caravans and wandering tribes of Nagpako were slaughtered when they touched the ground. Mutated Bulletes, twisted by the Destroyer Breath now resembled demons. They rose the earth like water. Undulating, rising, the bursting, the stone, and sand birthed the tunneling horrors from beneath. Crackling purple energies burnt the flesh. Hardened scales in rippling rows tore at the skin of any near. Claws hard as steel and teeth sharp as the blade tore any creature apart. Sigh monstrosities were these creatures. Named for the grounds trembling moan as they throttled to the surface, like the great breath of Potestatem.
Riz Ath and his Burgeonend now named the Synod of Wisdom now stood as sentinels against the horrors of the dunes. Nagpako necromancers slew and raised Hazfeni peoples of all races to fuel their undead armies in the southern Deathless Dunes. The Sigh were one of many problem. They stood apart when they finally attacked an Ascended Arrow unit.
The unit was led by the Burgeonend warrior Zanjo Three Blade. Zanjo has been sent to investigate the threat the Sigh posed. A surprise attack came upon the unit as they passed through a great ravine. Sigh beasts burst from the floor and walls. Crushing soldiers as they landed the Sighs surprise attack slaughtered nearly ten percent of the unit in mere minutes. Zanjo rallied his units eventually at the edge of the ravine and held the assault for six more hours before the unit was broken and he was killed.
After Riz heard one of his few Burgeonend has been slain by the new threat he mobilized his own unit to assault the Sigh. New to his powers Riz formulated a plan based on his few surviving reports and magical abilities. Before ascension, he was a well-known evocation wizard known for great control over the elements. Now with increased spell capacity, he marched into the great Sigh desert with himself, two other of the early Burgeond, and three hundred mixed infantry and cavalry.
There he met the Sigh. During their initial days, they fought small groups of Sigh who always pounced from dunes or the stone beneath the unit. Taking great losses for the small attacks Riz refined his plan. They tracked the small groups of sigh towards a larger swarm they suspected existed due to some exploration of the growing network of tunnels below the Sigh desert.
Cresting a particularly large dune they saw a great sandstorm. Within it dark shapes the size of huts and cows roiled in the sand, fighting a surviving Nagpako tribe that struggled in the swirling sandy air. Sigh launched from the peaks of the dunes to nearly a dozen feet in the air to catch any who faltered low. The Nagpako firing spells and arrows down, only a few hit the small window the flying Sigh gave. Riz ordered the unit to assist the Nagpako.
Charging down their dune the Sigh halted their assault. Only the running units' feet on the steep dune and the swirling sand filled the sky with sound. Nagpako glided, many wounded or tired from the fight. Riz raised his arms and began his plan, with a ninth-level spell of his own fruition, the now-famous Riz's Righteous Barracks. The dune shifted, rumbled and the spells finished. Sand swirling a second rumbling came. The ground sighed from below as if about to let out a breath. The battle began.
The spell cast rose a great circle of sandstone. Streaming inward the dunes compressed. Snaps and clicks and grinding synthesized the barracks under the soldiers quickly, forming hard ground to stand on and a short wall around the edges for them to guard. Soldiers ran for these risen walls as the whole barracks shook with impacts from below. 
"They have been blocked from below, watch the edges!" Riz bellowed. A crack formed beneath his feet and he looked down at it in concern. Explosions of sand rose from the edges of the barracks and soldiers yelled in surprise. The creatures that spewed forth from the pit were as small as dogs and as large as buildings. Long tainted claws of purple and black swung and scraped away at the sandstone they poured from. The ground continued to shake as more Sigh below dug upward through the harder ground. 
"Slay them quick, more are coming from below!" Riz directed at a nearby officer. He ran for the wall and began murmuring another spell. The sky above tore open and his spell took effect. 
The battle ended. The barracks formed atop the dune lay shattered in several mammoth sandstone chunks. Soldiers lay torn apart and a sea of Sigh were skewered or blown open amidst the chunky dune. Riz Ath breathed heavily atop the dune in his now-famous painting pose. One hand holding a large Sigh's claws, the other on his immense staff, still glowing with magical energies. 
His barracks spell went on to inspire hundreds more sand based spellcraft, many only Burgeonend could duplicate. Sigh were beaten back and feared the sight of a Burgeonds magic for a lifetime to come. But their horrors did not stop there as all Hazfeni know.