Norse myth reference

How is that for sport?' Russ nodded, barely able to speak. 'Good enough.'
The third time he moved first attacking with a baresark's fury. The old woman met him, her spindle limbs against his. He pushed and strained until the sinews stood out on his neck. He might have pushed a mountain back with greater ease. The crone would not budge and so Russ pushed all the harder. The dint of superhuman exertion, he forced the crone back half a step, bringing forth a gasp of amazement from the man-wolves. But the mightier the effort he exerted, the quicker his strength fled and this time, without the Erl-mother doing ought but hold him in place, he sank to the ground and the chanting of the wolves resumed its prior volume.
...
	Russ gave a confident smile. 'We shall see,' he said. 'The old woman. She is bad wyrd, a foe no man can beat, the fate of those who do not fall in battle. Age slaughters every warrior in the end, if he does not sleep upon the red snow. Is the Muspjall not her domain, staffed as it is by her victims?'

Wolfsbane