Assassin's Creed Valhalla Siege of Paris Defeat Sigfred with Roll Counter Attack and Plague of Rats. And it comes down to this, as the Valhalla hero needs to defeat Sigfred, and with that the old ways of the Vikings in Francia. The hero has more than amassed a variety of skills and abilities since the beginning of Assassin's Creed Valhalla, and is rather unstoppable even at quite a few significantly lower level compared to the boss enemy. Use counter roll backstab strike, and also plague of rats. Not to forget the ever useful Valkyrie Bat Wings dive, and automatic heal up when not being damaged.