Fortress of the Fire Giants

You're ready to infiltrate the fortress! Loki's invisibility spell makes Thor sneeze – good job you had nasal spray. The fortress layout and timing of the guard shifts will just allow you slip by. You wouldn't want to fight the Fire Giants.

You manage to sneak into the fortress. A tracking spell tells you the spindle is in the next building over. The heat of the roof means you must move quickly.

You find the spindle and use your power to disable the traps that are holding it. Loki gives it to you in a bag which he has woven shielding magics into. Hopefully it will draw less attention this way.

You sneak through the training grounds and discover training dummies that look like Thor and Loki. Is Surtur planning an attack?

You escape through a waste chute, and with the spindle in hand, it's time to leave this realm. Loki intends to take you to Niflheim, but the shifting ley lines are making it difficult.

You start a rockslide to block the path after you. Loki creates a portal but it vanishes too quickly to use, and the guards are after you! Loki takes the spindle to draw out those monsters. You should be able to use their portals to escape.

You have portals...and also monsters. You manage to make it through a portal and are left falling through worlds. You'll end up in whichever realm is inhabited by your enemy.