Paradox

In a realm of yore, a man is awoken from what he had thought would be his permanent slumber, dying honorably while on the hunt, but now awoken, he is charged with the insurmountable task of slaying a great demon beast. This task being solely for the pleasure of a mischievous god. He is tasked to bring it to justice for this malevolent god's pleasure, can he do it? Can he regain the slumber he so desires?