The Shakallu Demon by Real-Janifer

The Shakallu Demon or simply Shakallu, is a powerful Demon of the Planes, that comes from Lurappu.

The extremely powerful Shakallu Demon (a dem nutkiae, as the Nnai) was responsible for the event known as "Descent of the Planes" where many Planes were "sunk/descended" from the rest and resulted in what is known now under the name of Lower Planes of Milegu.

Even today the Shakallu, the Demon of the Planes, dominates large areas of many Lower Planes.
How can he have survived so long? Actually, he has not lived the time elapsed since ancient times of Milegu to the Opening of the Planes ^{1, 2}  but locked himself in a Singular Plane created by himself and endowed it with broad powers, including the amost freezing of time inside: a split second within that Plane were thousands of millions of years in the outside.

He did this to avoid being destroyed: the Malignant, who enjoyed an enviable position before the occurrence of this event, were trapped in the Lower Planes and sought tirelessly for eons to carry out his revenge.

However, the Sinking eventually proved beneficial to the interests of Evil: the Lower Planes, exposed to the terrible turbulence of the Interplanar Fabric and very isolated from the rest of Plans (sometimes called erroneously referring to Higher Planes Materials), were the perfect place to create, train and hide their army until they were ready to launch their final attack to Prosperous Races Milegu and thus control the Keys of the Planes, the Final Structures and ultimately, the Milegu itself.

Demons of the Planes, of which the most powerful is the Shakallu Demon, acquired various forms depending with one minor species dealt, appearing to them in terrifying ways.

Although there are rumors linking Shakallu as the creator of the Soldiers of Evil (also known as Xontassseslisz'nurom), these rumors are not tested at all.

*¹: But could have, the dem nutkiae are indestructible and eternal.
*²: When displaying the opening event of the Planes (that was many millennia before the Descent of the Planes and to the Closure of the Planes), the chronicler shows that it is a very recent event [the Opening of the Planes] and perhaps this text is compiled shortly after the Opening of the Plans and in full beginning of the Interplanar War.