Born to a mother who could not name his father, and who..

Didn’t have the decency to wait to die at the hands of an elven guard until he was old enough to wean, the bastard child of any number of the orcish horde was raised by battle instead. His first raid and subsequent kill occurred at the tender age of six. Krog grew cunning, strong, and brutal.
He possesses neither empathy nor sympathy, nor any other virtues of the weak. By the time he reached adulthood, Krog had already murdered two clan chiefs in combat and taken their clans as his own. He then swiftly did the same to three more before all of the orcish clans named him War-King to preserve themselves, and joined his now massive army.
The elves and humans of neighboring provinces were defenseless against the might of his horde, and he raided with impunity, taking all, leaving none.

Though he would never state it aloud, he still harbors..

An unspoken blood feud with all of Elvendom, and is particularly brutal when raiding their settlements and cities. Having heard the whispers in the darkness of Inferion and taken them as visions through the interpretations by his Deathcaller, War-King Krog has begun his invasion in earnest. He plans to take the Soulforge and craft a weapon with which he shall erase the elven people and their allies from Kirth in a glorious genocide. War-King Krog is perhaps the most brutal being in existence.
His axe, though it possesses no magical properties, has become an extension of his body, and he wields it with strength of deadly purpose. Tolerance of weakness within his armies is considered a weakness itself, and swiftly eliminated… permanently. The orcs have mastered the art of aggression and take no prisoners.