To unlock this Trophy / Achievement, you’ll need to use the Power of the Raven ability. This will allow you to fly up to a Muspelheim Monolith in Svartalfheim, part of the Dawn of Ragnarök DLC. These monoliths are scattered throughout the region, hovering in the sky, so you can miss them. On each one you’ll find a landing area near the centre, where you will encounter some Muspel enemies. However, all you need to do to unlock the achievement is fly to one of these landing platforms. You can kill the Muspels there to regain some Hugr if necessary.