He's caged in the body of a brain dead host. Jacob was a down on his luck system AI. All of his hosts died one after the other. It wasn't his own life on the line, so why should he care. The high administrators reconized his ineptitude and devised a plan. They'd force him to experience a flesh and blood body once again. Instead of guiding a stranger, he'd guide himself. If he failed this time its over.

The world of greenland was experiencing an ice age and had little in the way of life. The humans scraped by in mega cities and below their garbage piled up into massive junkyards. Neither their technology or magic could stop the ice age or the legandary beast that heralded it. What if they had a beast of thier own? One that heralded the end of winter. Unfortunately, there were no monsters of summer available. So, they chose a monster that held a stage in its evolution capable of being thier herald. They just needed to alter a few genes.

The ancient cultivators saw the thousand year long ice ages as just another winter. They dressed warmly and lived on their high mountains unaffected by the plight of mortals. Only, a thousand years had already passed and this winter still hasn't ended.